Whenever you try to open the game running natively on Linux, it's completely mute. You can either switch to Proton and run the Windows version or you can do what I tell below.

Navigate to this path:


Of course, replace [SteamLibraryFolder] with the folder where you set up your Steam library.


You'll notice there are audio folders for Android, PS4, Mac and Windows, but not for Linux. That's right, simply rename one of those folders to "Linux" or duplicate one of them and also rename it.