I click on play, then the button switches to syncing for a moment then like i didn't click it in the first place, also when i click repair it is stuck at 0%. What the hell is this platform

I've got kind of the same problem. After downloading the game (either through Galaxy or manual download) and running the installer (no error messages) the games launcher starts and then crashes half way through. No error messages, nothing - a plain and simple crash.
Come on, GOG, the previous post with a similar message is over a month old and you don't seem to care - do I really have to change to steam to play this game?

The problem is the Larian Launcher and would be more likely answered in their forums....

So I finally brought my version of DoS2 to life again. The problem was a 'non working' nvcuda64.dll. I recently switch from a NVidea GPU to Radeon GPU. Although I uninstalled the NVidea drivers, the nvcuda64.dll was still there. And for some reason, DOS2 tried to run it. So this caused the crash.
I simply deleted the nvcuda64.dll in the windows\system32\DriverStore\ ..... (back up first;)) and everything went smoothly.
I hope this may help others who meet the same problem.