My computer is running macOS Catalina. I have Xcode installed but I cannot open it. I keep getting an error that maybe my OS version cannot run the installed XCode version. There is no update for my computer OS -- Catelina seems to be the latest it's eligible for. How do I get a working version of Xcode?

The error says something about Xcode cannot be installed on Mac HD and that version 11.3 or later required. But I'm betting there has to be an Xcode version for Mac 10.15.7 that I can use. But I cannot figure how to install that.