When clicking on the button “register now”, Chrome downloads the file subscribe.php. This does not happen when using the genuin Android browser.
Tested with two devices:
1) Nexus 7 with Android 5.1.1 and Chrome 44
2) Lenovo 7-40 with Android 4.4.2 and Chrome 44
Actually I don’t know where the problem could be, if you have the antibot option active on subscription steps panel and the browser is not abe to execute the onlod event on a document, it could not work. Try to disable that option.