The "download" button was only showing from your main page that lists all of your games but I found it. However, on this (or any of the pages) the when I click it, the screen pops up with "install" and an empty drop down bar with another drop down bar under that for my chosen destination (I. E. C-drive / destination folder). All of your games save for the Elven 1 and 2 have the same issue for me. The Install button on the itch app does the same thing, as I said.
Edit: Included a screenshot. The very thin almost invisible bar between the two drop-down bars is what I get when I click the "install" area that says "select" inside it.