Sorry, I only have created vlans on basic wifi not with wifiwave2 in conjunction with VLANs.
I think you only setup vlans the way I know on the device running capsman, the AC3 in this case and on the other devices you setup the vlans via some datapath commands.
I think its absolutely horrible that the documentation and videos dont help but even worse are the so called capsman lovers here who trumpet its benefits but have FAILED to provide a user article on how to setup wifiwave2 with capsman for the very case you present. A very normal case, an expected case, one that should be relatively easy to produce a decent user article…
Where are guilty bastads… …start writing one up!