Final Cut Pro issue

Hey,

I updated FCPX by mistake and now I have this message. I do not want to upgrade to Catalina because I've heard it is still unstable. Anyone know how I can get it back up and running?

https://preview.redd.it/10tn8xrsu4n41.png?width=425&format=png&auto=webp&s=ddbec900b5d347f2576995d6a724faf60e5694fa

Thanks!