Hello! Are you having an issue with the download button itself, or is your computer blocking you from downloading the game files?
This forum post might be related to your download issue: https://itch.io/t/1112356/cannot-read-property-build-of-undefined-error-when-try...
Basically, the game might not be able to download from the itch client, but you can download the game from the itch website (Take the url from the bar in the itch client and access the itch page of this game in your browser.)