I'm unable to test the game on mobile devices, so this solution comes from another user who experienced the problem. They say that they used a file explorer to open the html in Firefox (though I would think Google Chrome should work as well). I imagine this is so that the game recognises the source files and is able to load them.
Let me know if this information helps. If not I can get in touch with the user who suggested the solution and ask them for more help.