Are your students having difficulty turning in large files or sending things from Drive to Google Classroom?
Whatever it is, have them put it in Google Drive and turn in the LINK instead:
How to turn in links to Google Classroom
Google Classroom - Turn in a LINK to Google Slideshow, Document or Other Content From Google Drive
Tap the three dots next to the file in Google Drive (or Docs, Slides, etc…)
Tap Copy Link
Open Google Classroom Assignment and tap Your Work
Tap Add Attachment
Tap the Link option.
Paste your link and click Turn In.