BP was built using an older version of renpy. You need to enable legacy mode in ur joiplay settings to run the game. We dont officially support joiplay but that has made it work for many players who wanted to use it
Okay, it looks like newest versions of joiplay axed that setting, so you might need to go directly to the creators patreon to ask about it. In the meantime, i tested on an old version of joiplay and it works.
download both the old joiplay app and renpy plug-in here: https://www.patreon.com/posts/55240870?utm_campaign=postshare_fan&utm_content=an...
then you can get to the legacy setting here