Turn off autosave numbers, pages, keynote

Your only option is in System Preferences > General > ☑︎ Ask to keep changes when closing documents. With this set, Pages autosave is disabled, and you will know that because the red traffic light in the title bar will continuously have a black dot in it until you manually save the document. If you quit without saving, then it will present the following dialog (from macOS 11.7 and Pages v12.1):

There is also a dedicated Pages for Mac Support Community available to you.

Are you using the available Synology AppleShare over TCP/IP or an SMB protocol solution?

Hello cucocreative,

Thanks for reaching out to Apple Support Communities. We see you h ave some questions about autosaving on your Mac, and we'd like to help. From here, try booting your Mac in safe mode, to see if this happens there: Start up your Mac in safe mode - Apple Support

Also, when you create a test user, this can help with seeing if the issue is limited to just one location on your Mac. Try creating a test user account, and let us know if this is happening there: Set up users, guests, and groups on Mac - Apple Support

Let us know, and we'll go from there.

Regards.

In short, I don't know how to resolve the original dialog you mentioned. I cannot reproduce it here with macOS 12.6, Apple's v12.1 office applications, but especially with my ancient Synology configuration. Regardless if I choose SMB3 or AFP.

I don't use any RAID on my old DS-110J Synology, and I am wondering outloud if you are using a RAID configuration, and if that is fooling the Apple applications into believing that the RAID duplication of their respective documents is what makes it believe the document is in use by another user.

My DiskStation Management Software version is capped at DSM 5.2-5967 Update 9 on that old DiskStation, so I cannot offer much of a testing comparison to newer releases of DSM, Synology hardware and their interaction with Monterey. On macOS 12.6, and a manual SMB share mounted, the only dialog I get from Pages v12.1 is when I attempt to manually save after allowing autosave to quietly update several additions to a document on the Synology. It tells me that it is on a volume that does not support permanent version storage, so in otherwards, the File menu > Revert To is inoperable with SMB. This with Ask to keep changes when closing documents deselected.

Pose your question in the Synolgy community if you haven't already and see if someone else has encountered and resolved this issue.