The current version of Numbers (v14) requires macOS Sequoia or later for installation. Apple does not maintain past full installers of Pages for user download.
If you have never installed Numbers since October 2013 from the Mac App Store, then you cannot get the latest compatible version for Catalina. 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 Numbers is there with a blue cloud download icon, select that. A dialog will then offer to install the last compatible version of Numbers for Ventura.