The itch.io version of the game is no longer supported. I've waited a week (and 4 days on a second email) without response from Innersloth to my request for a solution.
The itch.io version does come with a Steam key for the game, but for people who have good reasons to avoid Steam (such as it having been a known health risk for over 18 months) that isn't a valid solution. If you own the game here already, open your "downloads" page and there is a link you can use to get a Steam key. Otherwise, contact Innersloth. I'm giving them a week from my second contact then I'll be contacting itch.io as the next appropriate step to take.