As your Students will be using Goodnotes 6 and not Goodnotes Classroom, their personal Documents and Notebooks outside of the Lessons you share with them will not back synced with Goodnotes Cloud, and instead will need to be either:
- Synced with iCloud
- Backed up using Auto Backup on Google Drive, OneDrive or Dropbox
- Backed up manually with Manual Backup
Pleas advice your Students to enable one or all of the above methods to avoid losing their personal work. Especially if they ever need to delete and reinstall the app.