When pushing a build, when passing the user/game you don’t need to include “.itch.io”. So this argument:
jpablocs.itch.io/applengers
Will become
jpablocs/applengers
You can see more details on butler’s documentation for push, more notably:
butler push directory user/game:channel user/game is the project you're uploading for example: finji/overland for https://finji.itch.io/overland — all lower-case