Hey Zoro!
I'd recommend redownloading the .rpa from our Patreon, as the servers here on Itch can be a little be wonky.
You'll need a Patreon account, but free to create if you don't have an account already. Here's the latest free release (8.0.9):
Also, make sure to allow the launcher all permissions. If nothing happens, closing and reopening the launcher can help, and in some cases, deleting and redownloading the launcher can help.
Hope this helps!