Aug 09 2020 03:23 AM
Aug 10 2020 12:57 AM
Firstly, you will probably need to turn on checkin/checkout on the document library the file is in to stop issues with users trying to save it at the same time. Co-authoring will likely not work anyway.
There is no way to let a user edit the file but then not download. There is a permission level to stop download called view only but this won't let them edit the file. You can stop them syncing the document library locally, which is a setting in the document library settings.