How to make Phtoshop Elements 11 work on Mac Os Catelina version 10.15

macOS Catalina won't run 32 bit applications, which is what photoshop elements 11 is, so unfortunately upgrading to photoshop elements 2020 is the only way to have a fully compatible photoshop elements with macOS Catalina.

https://support.apple.com/en-us/HT208436

The new photoshop elements 2020 is a 64 bit application that adobe says will work on macOS Catalina.

https://community.adobe.com/t5/Photoshop-Elements/The-future-is-here-Introducing-Adobe-Photoshop-Elements-2020/td-p/10647617

https://helpx.adobe.com/photoshop-elements/system-requirements.html

There's no chance to update old apps. Apple have decided we all need to be running the very latest software and forever blocked the old stuff. Frankly, it's too early to talk about Photoshop Elements, Adobe will surely release a new version in due course. It's strongly recommended to check the compatibility of every single app you own and every plug-in/filter before any new mac OS, and never never upgrade in the first month. This is called the "bleeding edge" by those who have been there.