I suspect the pairing is with each other. There is usually a button for this on each adapter.
Not sure where Wifi comes into this - they are Ethernet devices which use domestic power wiring instead of a direct cable.
Have you checked in Network Connections (right click Windows symbol bottom left of screen) to see if Ethernet is enabled? Otherwise the first test is to check that Ethernet works using a cable between the router and the computer. If that works then it should also work with the adapters, one connected to the router, the other to the computer, then do the pairing.
If you've done all that and they still don't work then most likely they are faulty. I've found they work very well but I guess they might give problems if too far apart or if they are on different power circuits..
Always pop back and let us know the outcome - thanks