Frame Challenge: They can be way more advanced than us but not in ways that matter.
They will be vastly technologically superior to us if they can travel between the stars.
This axiom is not necessarily true. There are plenty of ways that your alien race could be technological comparable with humanity in all the ways that matter for your story to work without being technologically identical.
Option 1: FTL is not as hard as you think
You are assuming that FTL travel requires a massive chain of technological development that we have yet to achieve. Yet our own civilization went from not having a basic understanding of the inner workings of an atomic nucleolus to using atomic physics to destroy entire cities in just a few years. Humans could easily, right now, be a single scientific discovery away from knowing everything we need to know to make our own FTL engines, and we would not even know it until we get there. In fact, there is already some very promising research into Casimir Cavities showing that a precisely made meta-material can in theory achieve perpetual motion using Alcubierre's warp metrics and quantum physics. FTL, or at least reactionless, relativistic propulsion, could be a near future discovery as soon as someone figures out how to turn these microscopic experiments into something that works at human scales. Especially if your version of humanity is already decades or centuries past our current technologically levels.
Option 2: Both races have very different technology trees
Another possibility is that both of our races have significant technological advantages over each-other, but just in certain areas so that one can not rightly be called more advanced than the other. They may have a functional warp drive, but maybe they have yet to discover computers or wireless communications or something like that. In this respect, both of our civilizations could look in awe on each-other's achievements, and neither have a significant advantage over all.
Ferengi technology is estimated to be generally equal to our own [...] We are no doubt (more) advanced in some areas, they in others.
~Data : StarTrek TNG
Option 3: Humans have a superior military tradition and infrastructure, despite being "less advanced" overall
They could have many technological advantages over us, but they have no history of war on their planet; so, if push comes to shove, all their fancy engines and replicators and stuff don't actually put humanity at a disadvantage because only we have pre-existing military technology which we've spent a very long time perfecting.
The military societal capabilities of a modern nation can not be built in less than a few decades even if you already have a good idea about what it is you are trying to build. This timescale gets even longer if you don't already have a mindset for warfare. The aliens could probably figure out how to turn out some basic riffles and IDEs pretty quickly, but effective tanks, smart missiles, targeting computers, stealth paint, etc... these take years of RnD followed by more years of industrial organization just to build the manufacturing facilities for.
Futhermore, just because they have over all superior material science does not mean they will know the right materials to choose for each purpose. If your aliens tried to make a bullet using their strongest, most light weight alloys it would make for a much worse bullet than one made from brass and lead. They could use their hardest synthetic diamonds to armor their tanks, only to find that they shatter like glass when hit by a cannon because they don't know that they need to layer hard and soft materials or use sloped armor to aid in deflection; so, even their best materials could fare worse than human composites because we fully understand what it is we are creating the armor for. They will not know they need to fill their hand grenades with a shrapnel material. They will not know that guns need sights to help them aim. They will not understand how to balance rate-of-fire, accuracy, ammo capacity, and stopping power. They will not understand the point of combined arms. They will not know that their heat, radar, and radio signals can be tracked, or how to hide them. They will not know that their networks need cyber security. Their children have not grown up playing violent videogames, watching war movies, and studying military history in schools, so not only do they not understand strategy and tactics, but they don't even understand that those are areas of study.
On top of all of this, it will also take them time to figure out how to turn any of their advanced technologies into viable weapon systems that might surpass human technology. When they see a gun for the first time, they will see the most advanced killing machine their society has ever faced; so, even if they have the physics to make a phaser, it's not something they have considered making before; so, their best idea at first will be to try replicate the gun until they understand guns well enough to know that a phaser could be better.
By the time they begin to understand warfare well enough to fight back, they could already be fully enslaved... or at the very least, the humans will enjoy enough early military successes to steal enough alien technology that by the time the aliens learn to fight, humans will be on equal footing in non-military ways as well.
Option 4: Humans are able to talk our way into equal footing
For this option, it could be that they are more advanced than us in every way imaginable. They could be an all out post-scarcity level society with a stable global government and a fully automated economic system. But because of this, it means their current generation has no concepts of primitive capitalism; so, marketing, propaganda and information warfare, office politics, etc. are foreign concepts to them.
So we just flimflam and negotiate our way into equal footing very quickly because we have a whole world full of salesmen, marketing specialists, and con-men packing a plethora of skills that these aliens' mammas never warned them about. By the time they understand what a Nigerian Prince even is, they've already given away the keys to the kingdom.
Option 5: They only packed for a "camping trip"
The trip between the stars is a big one, even for an advanced alien race. This means that the alien explorers/colonists will have to leave a lot of the comforts of home behind when they make the long trip to Sol. If room/mass on their ship is limited, and the infrastructure to maintain a lot of thier more advanced tech requires proximity to thier home world, then they will only bring a fraction of the tech that their society has to offer. So, while they may appear to be about the same tech as us, this is a big misperception.
Think of it like this. If you plan to go on a long camping trip, you might bring some basic hand tools, a tent, a lighter, food, etc., but you would not have a computer, microwave, air conditioner, or Apache attack helicopter. So, if you were to plan a time traveling camping trip to the medieval period, people would see your technology as different from theirs, but you would not seem all that much more advanced than they are. Likewise, an alien species that is only packed for an exploratory mission may appear far less advanced than what that civilization is actually able to muster.