I'm sorry, but it could be any number of issues. It would be impossible for me to go through all of them. I would try to see if it is just this game, of if other Ren'py games don't work either. If you haven't already, I would definitely try to download the game without the launcher too, to see if that works any better. Thank you for the interest! I hope you do figure it out. Maybe someone on discord has a similar issue?
https://discord.gg/HfAwqKf66J
I would like to know if the game crashes on you, or if it is just a black screen not loading. I've had that issue from time to time with Itch.io launched games. Usually a restart or reinstall works for me.