Yesterday I was able to get tplinkwifi.net to recognize my 902 and configure it, with thanks to Tony.

However, that turned out to be true only with an Ethernet cable from the 902 to my main router. 

Since I want to use client mode, I disconnected the Ethernet cable and wanted to connect the 902 to the main router's WiFI. It doesn;t happen.

On page 8, section 2.2.4 the 902 users guide says:

2. Connect your device to the router wirelessly or via an Ethernet cable. The Wi-Fi
network name and password are on the router’s label.

I;m not understanding. To connect to my main router's WiFI AP, I need to enter the key for the main router AP. I don;t understand how to enter the key nor do I understand why the 902 network name and password are needed.

And also I dont understand why a new 902 in client mode can connect to my normal WiFi out of the box. At that point, it known nothing about the Wi network it must connect to.

What am I missing?

Chuck