If you were a backer at $20 tier or higher when we released on Steam, you will have been provided with a free Steam key. If you were not, you will not have been - but I have ever promised access to PC on Itch to anyone.
I added Android sales on Itch because I didn't want to leave Android users (who can't use Steam) behind when we moved to Act V. PC support on Itch is planned, but it will take a while as we need to navigate some legal and technical hurdles first.