Deploying a APs on 9800 from Prime, is a bit different from deploying it on the 9800 directly. As you see yourself, AP deployment becomes the Site tag, which in a way makes sense - you deploy APs at a site, not "in general". The "Flex/WLAN group" is ...
The feature is implemented, just not in the way you'd expect, and how we're used to from AireOS.In Prime, go to Configuration -> C9800 Configuration Model.There you'll find the same configuration workflow, as you see on the C9800.
