Here's the (current) link to the ROM file being served by itch.io. It's on a CDN so it's got a strange looking address. (you can also see it in your browsers developer -> network panel by filtering on "game.gb".
https://v6p9d9t4.ssl.hwcdn.net/html/2314031/web/rom/game.gb
For baerheather: The ROM file is inside the zip file you upload to itch.io, often in a "rom/" folder and labeled "game.gb"
Hope this helps.