From that url I would follow point 6, but before that works the driver has to support WPA Enterprise.
[OpenWrt Wiki] Configure Wi-Fi encryption This shows that wpad-mini does not support WPA2 Enterprise, and some time ago i read from GLI that you should uninstall wpad-mini and install wpad.
Now it seems that is supported without web GUI. B1300 Connecting to a WPA Enterprise Network
I will give it a try.
Thanks