You should be able to just hit the Download button under the SSWK image and download the latest build. Is it giving you en error?
I'm unfortunately not sure why it wouldn't let you download the game. You can maybe try doing the download recovery via e-mail option here: https://itch.io/support
If that doesn't work, this sounds like something you'll need to contact itch.io support for directly as I can see that you purchased the game and should have access to it. I can confirm that other users are able to download the game from itch.io without issue.