I recently update my Mac to MacOS Big Sur Version 11.2.1. I had Adobe Photoshop Elements 11 running just fine until I updated recently.
The error message I am getting says the developer of this app needs to update it to work with this version of macOS.
Since your question is about Photoshop Elements, I have moved this from the Photoshop forum where you posted to PS Elements.
Elements has been updated by the developer and is available here:
So I will need to purchase a whole new version?