AutoSave should work with files saved to the local drive - Mac and iOS
MacOS and iOS both have access to an excellent cloud based file store which is system wide. iCloud Drive. Forcing Mac and iOS users to exclusively use one drive complicates normal process and adds uncertainty when it comes to where files are stored. Further more, files stored in One Cloud are not backed up by TimeMachine and therefore not available for restore or roll back via techniques that Mac users would be familiar with.
Enable auto save for any location, not just oneDrive.