As much as I understand, you try to get tagged WLAN adapter interface. For my understanding it is not possible (WLAN card doesn't support it), and this would be double tagging anyway.
When you mention connecting laptop to port in 20 VLAN through wired connection, what do you actually mean -- connecting to access port in VLAN 20 (than laptop interface is untagged), or to trunk with VLAN 20 tagged (than laptop interface must be tagged by tag 20 -- it is supported by most modern cards)?
Anyway, WLAN AP (any, not specifically Ruckus) will just add VLAN tag 20 to traffic coming from WLAN assigned to VLAN 20. So when connecting to this WLAN you essentially connect to access port in VLAN 20.
If you are connecting properly, but it still doesn't work, check if you are connecting AP to proper port -- usually if you can't get DHCP, it means that proper VLAN isn't actually present on AP port, or VLAN isn't connected somewhere on trunks if there are multiple switches .
Hope it helps,