Office365 autosave and collab editing on Synology?

We've just got a 423+ as our office drive, as onedrive wanted £1900 to add 1Tb to our storage!!!

So I set up an x: drive for all users but it appears that office365 will only auto sync with onedrive, with things like multiuser simultaneous use of a spreadsheet, isn't possible?

is there any way around this, or should I just move all collaborative documents back to onedrive?