What version of macOS is your MacBook Air running? Click on the in the upper left of the menu bar & select "About this Mac." What does it say under macOS? If it is less than macOS 14, you are probably out of luck. Apple does not maintain past full installers of Pages for user download.
If you have never installed Pages since Oct 2013 from the Mac App Store, then you cannot get the latest compatible version for Ventura or earlier. If you have, then launch the Mac App Store on Catalina, and log in with the same Apple ID as you used for the previous installation. Press cmd+0 (zero) to open the Purchased panel, and if Pages is there with a blue cloud download icon, select that. A dialog will then offer to install the last compatible version of Pages for your OS.
A 2019 MacBook Air can run the current version of macOS, so I suggest that you update your Mac. You can then install Pages, Numbers & Keynote.