The scene is looking good.
From the asset it seems all your atrium is in a single mesh? Did you merge it in unreal? is it already a single mesh in blender?
So you cannot generate a simple collision shape that will fit this detailed geometry.
Best solution is to have your atrium geometry a bit separated. at least the floors and walls are independent geometries on which you can put simple collisions.
I think you can also define convex collision shapes in blender and then import them along your fbx in ue to use them as collision for your static mesh, but I am not very familiar with that.
Quick workaround:
- you can go in details of your static mesh of your atrium and select “Use complex as simple” for collision complexity
- you can also put cubes, hidden in game, that matches your floors, walls and pillars.
Some info on collision here too: