The current pre-release of the client ("pioneer" in the version) is only compatible to itself. So you can only play with other testers. Please be aware!
Alright so I kinda found the issues and not at the same time...I finally was able to get the game to launch somehow by following this guide. https://steamcommunity.com/sharedfiles/filedetails/?id=175274474
I renamed both my sound and movie folders and ran it in compatibility mode for windows xp sp2