Hi, sorry for necroposting, but I just tried this on Linux, and I have the same issue. After starting the game, it tries to launch on Steam, but because I got it in a bundle and so didn't get a Steam key, I'm unable to play. In case it helps, I installed and launched the game via the Itch app, and I have yet to try standalone. Still, if you need more info, please feel free to ask.