Some pics from ZD might help (or not).
[With only a few devices it seems madness but when you have dozens or hundreds breaking APs and WLANs into groups gives you much greater control]
ZD gui, Configure, Access Points:
Create AP (antenna) groups
![Image_ images_messages_5f91c438135b77e2479c82ea_6e2c77f8a6441e9bbea5f6d68c70cf7e_RackMultipart20171010849011gpz-5fcb384c-ba68-4a6c-ab3d-b0453b000508-789909782.jpg1507650259 Image_ images_messages_5f91c438135b77e2479c82ea_6e2c77f8a6441e9bbea5f6d68c70cf7e_RackMultipart20171010849011gpz-5fcb384c-ba68-4a6c-ab3d-b0453b000508-789909782.jpg1507650259](/t5/image/serverpage/image-id/1132i90D00F0DE49F239B/image-size/large?v=v2&px=999)
then add APs to that new group
![Image_ images_messages_5f91c438135b77e2479c82ea_98ea9de1e50b05645d5c1d3836b47020_RackMultipart20171010371318d52-3aae30da-9943-4515-ad16-2eea85465260-191312156.jpg1507650325 Image_ images_messages_5f91c438135b77e2479c82ea_98ea9de1e50b05645d5c1d3836b47020_RackMultipart20171010371318d52-3aae30da-9943-4515-ad16-2eea85465260-191312156.jpg1507650325](/t5/image/serverpage/image-id/1133iC8FEE81761729CDF/image-size/large?v=v2&px=999)
Create WLANs
![Image_ images_messages_5f91c438135b77e2479c82ea_9831df68e5b4f56f92c0b19b722df67e_RackMultipart20171010729891xh4-2abb189e-c0ba-448b-b6bc-5620456278d5-72074764.jpg1507650589 Image_ images_messages_5f91c438135b77e2479c82ea_9831df68e5b4f56f92c0b19b722df67e_RackMultipart20171010729891xh4-2abb189e-c0ba-448b-b6bc-5620456278d5-72074764.jpg1507650589](/t5/image/serverpage/image-id/1134i7E64CF6643F1CD03/image-size/large?v=v2&px=999)
and add them to WLAN groups
![Image_ images_messages_5f91c438135b77e2479c82ea_a2359203cb5e1e152315bfaecc6bd1cf_RackMultipart20171010129126nvj-3f6de6a9-4d77-4719-931a-9722dae3d083-1967034666.jpg1507650743 Image_ images_messages_5f91c438135b77e2479c82ea_a2359203cb5e1e152315bfaecc6bd1cf_RackMultipart20171010129126nvj-3f6de6a9-4d77-4719-931a-9722dae3d083-1967034666.jpg1507650743](/t5/image/serverpage/image-id/1135i23979FA19C2240F1/image-size/large?v=v2&px=999)
So now you can go back to the AP group and select which WLAN group it will use - greyed out box at bottom.
AP groups contain APs and use WLAN groups to know what WLANs they should broadcast.
WLAN groups contain the individual WLANS and they use ACLs to allow clients by MAC. Simple, tee, hee. I need to rest.
Hard to get your head around but it all makes sense...eventually.
Max