In Steam, download the game and switch to the beta branch “translations” (pw: ZDWVUN9YJBH754LX).
You should now be able to download the Linux build. During this test phase, and to make my life easier, the game will only be on Steam. Once released it will be on GOG.
This is a post-alpha, pre-beta build, so expect problems. Some players are reporting issues if you previously played Delores using Proton. If you have issues where it’s downloading the windows files and not the Linux files, switch to the Steam Linux Runtime. Only a guess that this is what the problem is.
Please post all issues with Linux in this thread.