I save everything to my business OneDrive.  Office autosaves any file changes, then uploads to the cloud.  Then you can view on iOS, through a browser, or it downloads onto your other machines.  It will store everything synced on the local drive of your other machines if you set it up that way, and keep it synced.  Otherwise it may take a couple seconds to download the most updated file from the cloud and open it.  If you run out of hard drive space it saves stuff to the cloud and downloads it.  You can force files to stay downloaded locally for ease of access.  Microsoft does not guarantee you a backup in any way with this system, you are supposed to have an alternate backup.