Pages

You may be able to get the last compatible version of Pages (v11.1) for Catalina. Launch the Mac App Store signed in with the same Apple ID as you have downloaded Pages beforehand. Press cmd+0 (zero) to open the Purchased panel, and click the Update button for Pages. You will get an initial dialog sharing that you need a newer version of macOS. Accept it, do not click Cancel. A second dialog may appear offering to install the last compatible version of Pages for Catalina. You know what to do…

If there is no instance of Pages in that Mac App Store Purchased panel, then there is no means for you to get the application from Apple, and it would be very risky to get a copy from any other Internet download location.