First of all make sure that you are launching the game via GOG Galaxy.
Next make sure that the game and GOG Galaxy are added to your antivirus/firewall trusted/exception list, please add the following files to them:
C:\Program Files (x86)\GOG Galaxy\GalaxyClient.exe
C:\Program Files (x86)\GOG Galaxy\GalaxyClientService.exe
Restart the Galaxy Client afterwards.
If the above doesn't help please also verify game files using the More > Manage Installation > Verify/repair function available from the game's card in Galaxy.
If the issue persists, please create a support request.