If you downloaded the web version and tried to run it in a browser, that won’t work for “security” reasons on an Android device; you’ll need to use something like JoiPlay.
If you’re talking about playing the web version online on this web page, I just checked it on a few devices and it works for me right now. Itch.io is pretty reliable, but every server hiccups and sputters from time to time, so it may just be something like that.