Okay, I did a quick unwrap of your meshes in Blender (see attached .obj) and some dressing up in Substance Painter. Once you get used to the workflows it's all quick and efficient. This didn't take longer than 20 minutes altogether.

Happy learning :)
Sven

PS: I made three UV maps (one for the wall, one for the windows, and one for the door). To work on them in Substance Painter you have to choose them. Also the orientation of your meshes in MoI is wrong, the wall is lying on the floor, not standing upright. I didn't change that