The first time you save your open Pages document and give it a real (not Untitled) name, Pages autosave and version control will be activated and unless you are saving off to some non-Apple cloud service, autosave should preclude your needing to perform manual saves. You should also be using Apple's Time Machine and an external drive to backup your Mac every hour it is turned on. Sometimes, Pages documents can get damaged and a backup can save you hours of work.
If you are using any anti-virus or so-called Mac cleaning applications, I strongly recommend that you remove them per vendor removal instructions. These are unnecessary and can be your undoing by interfering with applications and the operating system.
Reboot your Mac. Ensure that you have Pages v13.2 and have updated your Mac to macOS 14.3.
Press and hold the shift key while launching Pages. That will prevent it from loading its last saved execution state, and may help you get past the crashes. You would only need to do this after a Pages hang or preceding crash event.