It wasn't working for me either. Good thing I'm not the only one!
Do I have to set up a provisioning profile? Or does simply adding the UDID take care of registered my device?
Thanks
the provisioning files are not needed. You just need to add your device's UDID exactly to the portal site.
You can simply just go into itunes and click the device serial line and keep clicking until you see UDID and then right click to "copy UDID". No mistakes this way.