At best, you can only get the v11.1 Pages, Numbers, and Keynote applications installed on Catalina at this point. The current 12.2.1 versions are strictly for macOS Monterey and later.
What dialabrain said.
On the other hand, if you did previously install Pages, Numbers, or Keynote with the same Apple ID at some point in the past after Oct 2013, then you can get the last compatible version of these applications for Catalina. That process would entail launching the Mac App Store, signing in with that same Apple ID, and pressing cmd+0 (zero) to open the Purchases panel. If these applications appear there with a blue cloud symbol, click that and you will be offered the last compatible version for Catalina.