Steam allows users to select Proton Experimental as the Steam Play compatibility tool for non-steam apps but does not auto download it if it is not present on the system. Trying to run the non-steam app from within Steam will result in a "failed to lauch" error.
Workaround:
Set Proton Experimental as selected as the Steam Play compatibility tool or a game native to Steam,
Launch the game.
Steam will auto-download the necessary files .
Return the Steam Play compatibility tool setting for the native steam game back to the default.
Thereafter Proton Experimental is availble for use by non-steam games.
Steam allows users to select Proton Experimental as the Steam Play compatibility tool for non-steam apps but does not auto download it if it is not present on the system. Trying to run the non-steam app from within Steam will result in a "failed to lauch" error.
Workaround:
Thereafter Proton Experimental is availble for use by non-steam games.
You may want to add this advice to the tutorial.