First, try to add material at the ceilling and then a transparency material at the top, so the sunlight can reach the interior.
Second is to set the scene you want and make some walls to hidden groups or use section slice, to delete the walls for sunlight.
Otherwise use renderapps, suggested before.
For windows try the youtube videos as suggested, but also my videos on youtube called Fenster1 and Fenster2 which exclaim how to make windows in double walls.
Although it is in German language you could find it usefull.