I downloaded the game files, mounted the .iso files and added the game to setup.exe to my steam library and installed the game under the mountpoint. When i click play in steam i just get back to the installer. Running the SkyrimSe.exe in steam(located in the CODEX directory) doesnt work. I use Arch Linux.
Use Lutris instead. Add the EXE, install it, change the launch EXE to the correct file.