[2022] Why don't the launcher work?

Where have you bought EUIV?
It'll appear only if you have bought it on Steam and linked your Paradox and Steam accounts. Epic and other stores don't provide teh necessary API to Paradox for it to appear.  

You must have run the launcher from the desktop shortcut, which is a standalone mode for users who do not want to run Steam. It does need a separate game installation if used that way, and in any case EU4 was never ported to that platform.

Epic games must be run from the Epic launcher.