Ref: https://forums.sketchup.com/t/cannot-save-to-google-drive/86135?u=techuser

Please reference an earlier, closed case from other users:

I too am unable to access a student’s Google Drive to save a project created in SketchUp. The student’s Google Drive folders to not appear when navigating there. The work-around has been to use SketchUp Make, create a project there, and then open that project from SketchUp for Schools.