First probably check you have the game downloaded from the Epic store. If you have the Alpha version, you're not granted any further updates and you need to buy the game first.
After that, reinstalling the game (not the Epic launcher) including download of the game files from the Epic store should definitely install the most recent public release of the game. Or the Experimental branch if you choose so. But I believe the "stable" is just ahead or at the same point as Experimental at the moment.