I am on Linux Mint XFCE, and I have installed the flatpack version from the software manager but cannot use latest alpha. Although update manager is noticing me the game has a new update, it seems there is something wrong as it does not update the game when download finishes. Also I am a new Linux user, just installed the OS some days ago, so I might be missing something. Anyway I am going to use 27.0 until a find the way to build the 27.1 as @ffm2 suggested to me.