Will not open when i doubleclick on it

Hey,  @robtl. Welcome to the Lightroom Community. I'll need more info to help you figure this out. Please share the version of Lightroom & operating system you are working on. Do you see an error or pop-up? Please share more details, like screenshots or video recordings of what you see.

For now, try this primary troubleshooting step to ensure Lightroom has required permissions on the macOS: https://community.adobe.com/t5/lightroom-classic-discussions/quick-tips-how-to-give-full-disk-access-to-lightroom-classic-on-macos/td-p/12913413

If this does not help, try this/l

• Go to the following location to launch Photoshop via terminal
  In Finder > Application Folder > Adobe Lightroom > Right-click on Lightroom.app > Show Package Contents > Contents > macOS > Lightroom - double click to open.
• If Lightroom does not launch, look at the terminal window and copy & share the results with us here.

Let me know how it goes from here,

Thanks!
Sameer K