CAPTIVE PORTAL on Balance 710


I have Peplink Balance 710, Hardware revision 3 with Firmware 7.0.2 build 2167.
I would like to enable the Captive portal to a specific SSID and specific vlan .
Vlan ID - 56-57
enable Use VLAN Pool
vlan 56 -
vlan 57 -

Peplink Balance 710 connected to CORE SWITCH (FOR VLAN) and with DHCP SERVER (Windows 2012 Server)

If I am going to enable the Captive Portal, only LAN appeard, I cannot find the list of VLAN that is assigned in the SSID.
Is the captive portal applicable only for the VLANS created in PEPLINK BALANCE?

Is there any option in the configuration ,if the VLANS are configured in a core switch and not in the PEPLINK Balance.

Thank you.