I can't seem to see it in the itch app. In the browser, I can see the option to launch/play. If WebGL is blocked by your browser, Godot will report that in an error. In Librewolf, I believe something else is blocking it even when WebGL is enabled.
Brave (and, likely, most chromium-based browsers) and (unmodified) Firefox worked right away for me. c: Might can give those a try.