Updated rating to a 5/5 after the quick response and help from the developer. There were originally some issues with the asset for Unity, these have been resolved now, and it looks great!
Viewing post in Japanese Apartment - low-poly PS1/PS2 style comments
Hi. Sorry to hear about the problems. We also used this asset before in Unity but exported the pieces out from Blender separately. The fbx files are mainly for non-Blender users (like Maya, 3dsmax) to be able to open the mesh in their program and export the pieces out to their desired engine.
We will prepare a Unity package for you and update this page! Please check back in a few hours.
We've upload a package for Unity! Please download "Japanese apartment Unity-URP.zip" It's made for URP. If you're using another rendering engine, you have to convert the materials.
As for baked lighting, the meshes have a few overlapping UVs which is a common technique for low-poly and small texture sized PS1/PS2 games. So I think that's creating the problem with baked lighting. In Unity, did you already try turning on "generate lightmap uvs" on all the models? If not, that may fix it.