Why do you assume anyone would download it, without reading the description?
The button changes depending on screen size and if it is paid/web and other factors.
Even if you have custom css privileges, you are not allowed to change the user interface. You would have to have promised not to do so, when being granted those privileges. I cannot understand why Itch even has this feature. It is a bad user experience and very concerning when developers get smart with their page and remove elements. Seen it several times.