check the setting in the picture below:
If you have changed the default certificate for the controller, the controller will not respond to securelogin.arubanetworks.com and the "submit" will not happen. If you also changed this ip address to a specific one, outside of the controller that the user is on, it also will not work....
Did you change the ip cp-redirect-address on that local controller to ip address on the guest VLAN of that local controller?