Error while 3D-printing because of openings in Archicad model

[LeonardWeber]

I've used openings in Archicad to make more detailed windows by subtracting specific shapes. But after exporting as a .stl for 3d printing I get some errors in Cura, the slicing software:

"Textures" are missing in the windows and when sliced, a whole part of the house is missing. Any ideas or even solutions? I've already tried to use MeshLab or Fusion 360 to export it again as a .stl but it didn't help.