Thanks for trying Pete, sorry to hear you can't access it. I'm not too sure what the issue is without telemetry but you're the second person who faced issues. Might be a browser compatibility issue, or a fringe-case bug with Godot exporting to HTML.
Thanks for the info on what works and what doesn't plex! While I can't test as I don't have a Mac, this helps as I can include a downloadable in future to cater for Mac users!