Arris VAP4641 setup Mess witout WPS ?

Hi.
Dont know if its the right forum, but I have this Arris VAP4641 AP, and want to use it to extend my WIFI, but as I see the only option is to use a Cable, if you want to extend by an existing Wifi connection, you need to use WPS, which I cant use. Is there any workaround ?

There is a label with a default SSID and Password on the device. You should be able to plug it into power and then connect to the device via WiFi using the default SSID and Password on the label.