Good day?

Ive flushed my TP-LINK WR941ND with DD-WRT and it works find. Ive created a Virtual Interface AP for my guest Wifi. Now I want to use the captive portal of Pfsense to work with my DD-WRT Guest Virtual Interface AP. Ive already setup the pfsense in Oracle Virtual Box and its working fine. But how can I use the captive portal of pfsense with my DD-WRT AP?

Thank you!