first of all, just to get the obvious out of the way, did you enable the module and then (soft) reboot your phone?
After the reboot, go into the app, buttons, "add new key", press the key you want remapped like "back", press "ok". now the "back" key shows up. click on it, click on "add new condition" and then "screen on", now "screen on" shows up, click on it and you can define the click action and long press action to be reassigned to the "back" button. repeat the same for the "menu" key and done!