Not able to download iwork apps in macOS Catalina 10.15.7

Pages, Numbers & Keynote now require macOS 11.0 or later. If you have downloaded them in the past on your current Apple ID, open the App Store, click your name on the bottom left, and you can download a compatible version from "Purchased". If not, you can't.

Per dialabrain's recommendation, the last compatible version of Pages, Numbers, and Keynote for Catalina is v11.1.