I don't know how to play it on mobile, but on any browser it just says this:
"Error
The following features required to run Godot projects on the Web are missing:
Cross Origin Isolation - Check web server configuration (send correct headers)
SharedArrayBuffer - Check web server configuration (send correct headers)"
Weird... I had that same error at first, but then I enabled SharedArrayBuffer support on my project's page and it's worked fine for me after that. I don't really have any more ideas. Only thing I can think of is to disable some extensions like adblock or userscripts, in case they are interfering with the headers somehow.
As for mobile, you should be able to open up the same page as on desktop and if all goes well it'll just work.
