1 ) in Lutris change wine version to " custom " and put the path for the GE-proton executable in the input. ( GE-Proton9-21 worked for me )
2 ) Repair / Download the game of your choice ( you might still get the error )
If you get an error again that’s fine close battlenet .
3 ) revert back to the default wine version and the game should now have the play button
cheers