Apunami: In my opinion you should try the repair option by opening the game page in your library and clicking the button next to the play button towards the right in which you can find manage installation and then there's verify/repair on which you should click one and the file repair process should start after it. It basically repair the game file if it's broken/partially downloaded so it might solve your problem hopefully. DM me if that doesn't solve your problem I've got some more tips. And in case none works you can get help from the gog support so please don't lose hopes :-).
Imma try this solution real quick just gimme a min. Will edit this post if your solution works mate.
Edit: It worked fella :))))) thanks
