IDK, maybe your walking around is like what my counselor is always telling me about my neighbors. When you live in an apartment you hear a lot of incidental noise, you can’t have perfect quiet in an apartment . It’s just expected that you are going to hear your neighbors, especially if you live in an older building where the building codes weren’t as strict and the walls are thinner.
I don’t know. Sometimes you have to move around at night. I would try to move as little as possible at night though, and if you know where their bedroom is located, avoid walking in that area.
The landlord should make a upgrade if this continues to be a problem.
Maybe walk around but wear thick socks or slippers. Maybe if you just like staying up late, just stick to the kitchen or the living room and sit and don’t move around a lot.