I don't understand what's your problem exactly. You first have to get your CosmosEx on your network, either by wired ethernet or by Wifi.
If it is connected, you can check the webpage http://192.168.0.55
(replace 192.168.0.55 with the IP of the CosmosEx, you can get it from your router, it is also displayed when CEDD driver is loading on the ST)
I don't know why you tell it will not work with WPA2... well it depends on the wifi Card. Are you using integrated Wifi of RPi ? or a wifi dongle ?