For some reason, some players have not been able to access the Steam key that comes with their Itch.io purchase.
It seems like some sort of error, and I've contacted Itch.io support.
I'll update this thread once the issue is resolved.
Got it fixed by the itch team.
I made an itch.io account for your wonderful game as Steam controller support is awful, but felt I needed the key just so I could screenshot the game and let all my friends on the Steam client know about it, worth the struggle!
I hope A Short Hike does amazingly well for you :)