The last update of Pages for Mojave is version 10.1. You cannot install anything newer than that because the current versions (12.2.1) in the Mac App Store require macOS Monterey or Ventura. Apple does not keep past full Pages installers available for user downloads.
If you previously installed Pages from the Mac App Store, the Mac App Store should allow you to get the latest version that is compatible with Mojave, but nothing newer. Launch the Mac App Store and sign in with the same Apple ID that you used to install Pages previously. Press cmd+0 (zero) to open the Purchase panel, and there should be an Update button adjacent to Pages. Click that, and do not cancel any dialog that is presented afterward. Either the first, or second will get Pages v10.1 installed.