OK, there actually two problems with this scenario:
- Protecting soldiers from the overpowering force of the golem that
not just bashes but also shoves and stamps anything trying to stand
up to it.
- Golems are easier to armor than living beings and as
expensive hardware they'd be protected from any damage normal
So it is not enough to worry about armor, you also have to think up weapons and tactics that allow normal soldiers to stand up to golems or the armor is pointless waste of money.
For tactics the only methods a relatively low cost troops can stand up to something as obviously magical and elite as golems are either fortifications or swarm tactics, We can ignore fortifications here because the implies field of battle and golems would probably be fairly good at assaulting light field fortifications.
Swarm tactics means that the soldiers will surround the golems in a densely packed mass that repeatedly attacks the golems from every direction. Groups would probably try to focus on a one golem at a time and pull it down by breaking its legs before moving on to the next one. A golem reduced to crawling would then be left to specialists to deal with after the fight is over. Presumably the golems could be tangled up in nets and then either magically taken over and repaired for use against their former owners or simply hammered apart slow but certain. It might be possible for the assault groups to be followed by the entanglers during the combat so that they could be properly neutralized.
For protection (the actual question IIRC), I am thinking cages. The golems would presumably be rather large so it is not necessary to cover soldiers fully, bars spaced close enough that the golem can't strike between should be good enough. Material could be wood with metal reinforcement, which depending on available wood could be light and cheap enough. The cage armor would be rounded on top and hexagonal then seen from top so that in densely packed mass of soldiers the cages would support each other against shoving and pushing. Of course the cages would support being braced against the ground. A group like this would be rather difficult to shove out of the way and while the golems might be strong enough to lift the individual soldiers, they probably wouldn't be able to do so casually without opening themselves to attacks sides and behind. Which is why a swarm is needed.
The cage would be carried and kept off the body by leather straps attached to harness on the torso. The straps would be slightly elastic to resist snapping and together with the mass of densely packed soldiers this should give decent protection against bashing. The cages would go down slightly below knee level so that the soldiers under attack could draw their legs in to avoid leg injuries then bashed and shoved. This would additionally automatically brace the cages against the ground. It should be possible to attach some light shielding to the cage to give protection from missile weapons without compromising mobility or visibility too much.
Obviously a group like this would need to be very strong and very well trained to move together for this to work. But Swiss pikemen and other similar groups had roughly the correct level of discipline and training, so it should be possible. But it would be an elite unit.
And for weapon... I think that taking down an armored golem would be roughly similar to breaking a gate in difficulty. Normal weapons would be almost useless. You need something like a battering ram with a point to do it properly. But actual battering rams are rather clumsy and would be easy for golems to break. But with the cages being hexagonal, a dense mass of soldiers charging could with proper training apply the momentum of the entire group, including those heavy cages, to single weapon braced against the cage of the soldier in the point. The force should be enough to damage even a golem. The actual weapon would be something like a very strong spear with a hook in the shaft that goes well around the bars of the cage.
So the soldiers would surround the golem, for a number of wedges, charge in simultaneously (or at least in rapid succession) so the golem can only stop one of the attacks efficiently, withdraw slightly, and charge again. Repeat until the golem goes down and then move to the next golem.
This all presumes that the golems are "military grade": large, strong, and armored to defeat normal soldiers. If the golems are of a more generic variety, you should be able to take them down with bolas and nets, essentially reducing my two stage take down and disable method into one stage that can be done by a single group. In such case, the soldiers would be lightly armored and mobile. The golems simply would not be given an opportunity to hit them.