It sounds like you only played the Demo. Try downloading the second file as well.
The Demo is an isolated portion of the main game. I'm working on it separately to iron out the technical kinks before integrating it. You can see this post for more details: https://www.patreon.com/posts/59518356.
Does the client not allow you to download the second file? I didn't realize there was a client. I will take a look when I get to my PC.
Oh, it does. It's just that it doesn't prompt me for which file to download. I actually have to install the demo first before I am able to manage the installation to also download other files. Which I don't usually think to look for, since the other files are usually versions for other OSes or earlier versions of the game, not supplementary files.
I think you could reduce confusion by calling it something other than Demo. Though I don't really have a good suggestion for what to call it, since this isn't a common method of distribution.