Olfactory communications is very common in the animal world (even humans engage in it... albeit it, not as strongly as our sense of smell is one of our least developed senses... we still use it for a lot of important instinctual reactions). In fact, it's one of the primary communication methods used by many social insects. Ants, for example, use scent markers to follow trails to sources of food. As they return, the markers become stonger, attracting more ants to the food. Flowering plants use scents to attract pollinators to their pretty flowers... lean in for a sniff or a drink of that sweet, sweet nector, come away with a body covered in pollen... go to another flower and do the same... and pollen touches the stamen and boom... that's how fruit is made (it's the birds and the bees!).
Other animals use scent markers, often as a form of messaging systems. Canines (especially males) often encode scent markers into their urine, leaving a message for other dogs to find later that and pick up and recieve the message. This becomes more frequent of the dog is in a new area and male dogs will often mark areas even if they have empty bladders.
Even among humans, we have some strong involuntary reactions to certain scents... but it's often used to enhance taste... and since we evolved from foraging omnivores, developing a refined sense of taste helps us to understand what's good to eat and what needs to be avoided... That thing that smells sweet? That's good you can eat that (it has sugar, which tastes sweet and has ALOT of energy to make a body go). Bitter? Leave it behind... it's icky (Because most alkaline metals taste bitter and all alkaline metals are poisonous to humans... and among the worst poisons too, as hard metals can't be processed by the body meaning they stay in you for life and the build up will kill.). Spicy? Also poisonous... but you can eat small amounts (Most sources of spicy food are biochemicals used by plants as poisons to fend off animals from eating them. Unfortunately, being evolved from foraging omnivores means humans have some pretty tough digestive systems that can break down poisons... not only does spicy biochemicals don't work on us, we've actually forced some plants to get even spicier... so we can eat them. Spicy foods also will cause us to activate our sweat glands in response... which cools us off.).
One of the most consistent ways we communicate using smells... is one of the most disgusting things we do... and there's a good reason for why it's so disgusting... and why the smell is so potent. The smell of vomit is one of the most potent smells to a human being and is so terrible, it will cause those who smell it to almost vomit themselves... but this is actually a good evolutionary reason for this. As a social animal that lived in large groups of omnivores, sometimes the hunters/gathers brought back something that they shouldn't have... and they eat it... and their body tells them that was a bad idea and get it out the fastest way possible. The poor fella "tosses his lunch" but he brought that rancided ick home for everyone to eat... and now the whole tribe is about to eat it... best signal them to not do it by sharing in the pain... some might have... others might not... but let's make sure we don't kill the whole tribe... hence "vomit" is one of the worst smells for a human to experience... better to starve and eat something good for you later, than to foodie around and find out.
That all said, most instinctive behavior is learned by species with high intelligence (especially mammals... babies needing milk means at least one parent is there to teach her kid how to be... whatever they are.). Mom teaches the kid how to find food without her around... kid gets the training they need to survive and by the time mom kicks them out, mom has hopefully trained them enough to fend for themselves (sometimes dad helps too. We may joke about Tiger Mom sterotypes, but real Tiger fathers are known to be so protective of their kids, they will kill cubs that don't belong to them to give their kids an edge... then kick them out of the house when they start getting old enough to have their own babies.).
Scent plays an important role because finding food is usually done by tracking a scent (Humans actually didn't evolve this... but we were so good at finding food through other means, we didn't need it and ended up in a sybiotic relationship with the one animal that could hope to keep up with us... the dog is man's best friend because we use similar hunting tactics to them and they have skills we lack and vice versa. Dogs have better sniffers, we have better eyesight, communication skills, and endurance.).