Hi, Are you still experiencing this issue?

If so, which version of Proton are you using? I'm playing the game on Manjaro Linux on my desktop and I had to try a few different proton versions before I got this map to work.

The version I'm using is Glorious Eggroll Proton version 7-5, which is an unofficial fork of Proton that you'll need to download and install manually from Github, but that's fairly easy to do. The version I'm using is an older version, but the newer one should also do the trick, though you should be able to download previous versions if for whatever reason the newest version does not work.

Hope this helps!