Ok when making a building in bender, how do to make it so you can actually get through a doorway, I uploaded the mesh, but I can't seem to go through the doorways LOL.
I would suggest you take your building as a copy into a new file and strip it to bare bones what you'd need for physics, reducing any unnecessary geometry possible. The normals, textures, UVs don't matter.
You can upload it either as a separate file on it's own and attach it as the main prim with the physics setting to prim, or as the physics on the original upload.