Ok I managed to get the CD key in. But i'm still getting the message "battlenet has a new software update available updating now" whenever I launch gog in war2combat. I can't log on the gog server with it.
Software update means something wrong with exe. You should start war2 using War2noCDloader.exe from the combat 4.4 folder.
You can also right click a Warcraft II BNE.exe - properties - detailed. And then - version should be 188.8.131.52, not 184.108.40.206 or w/e.
Then everything should be ok with software to not reuire any updates...