Comment by Neil44

The issue with a client app backing up dropbox and onedrive folders on your computer is the files on demand feature, you could sync a 1tb onedrive to your 250gb laptop but it's OK because of smart/selective sync aka files on demand. Then backblaze backup tries to back the folder up and requests a download of every single file and now you have zero bytes free, still no backup and a sick laptop. You could oauth the backblaze app to access onedrive directly, but if you want to back your onedrive up you need a different product IMO.