Hi, i can't install kao 2 on my GOG galaxy, it runs steam platform, why??? Very strange, I need to install GOG version without Steam. Thanks! Very strange issue!

Install or start the game?
This - laucnhing (not install issue) game in Steam instaead outside of Steam - possible to happen if Steam is already started, and game have steam lfetovers files, and you linked accounts.
GOG Galaxy version do not have such steamclient dll's. hat hsouldt be happened...
Very strange issue indeed...

You still can install normal GOG version downloaded if from GOG Galaxy or directly from your account page via your standart browser. And later optionally add it to GOG Galaxy as already installed game (as third party one, or as GOG version).