I got it long ago, and during the sale for $5.00, and when I had this same update issue, the developer responded to me with the wait news. I believe the developer said is an itch issue. I have since received two updates. If the free update model for those buying at the sale price has been removed, it is news to me, and definitely a bad thing going forward, but he/she seemed nice about it and even said there would be a steam key for the $5.00 purchasers. I am sure he or she will examine the posts and let us know something shortly. The developer appears to be fair. Afterall, it was the sale purchases which likely provided the revenue to continue the project. I paid $1.00 so long ago, my original save files couldn't be upgraded. People like me are the reasons you can advance the story.
Additionally, I can see the link for the new update, but it does not allow me to see the files, so it seems to be pending. Like I said, the developer said it is an itch issue. Just give it a little more time.