Hello there @Del_xe!
Checking around the community, the IS-IN-FC02 error tends to pop up from time to time, in different cases. In short, the installer is having a conflict when attempting to write on a file during the install. In MacOS, this is usually a permission issue.
So, the first thing to check, is to ensure that the Epic Games Launcher has the proper permissions to write on your disk. This setting should be at System Settings > Privacy & Security > Full Disk Access.
You should also clear the failed launcher’s cache, via deleting ~/Library/Caches/com.epicgames.EpicGamesLauncher, then testing the install again. If the issue persists, I would suggest removing the launcher all together, and reinstalling it from scratch.
There’s an extended thread with more details to check, you can find it here: