[HELP] IPTV port with VLAN

Hey guy, would like someone enlighten me how to setup IPTV interfaces.

I have been scratching head for over 2 years for now. In here most of my country market selling normal router like asus brand or TPLink, there is wizard setup internet, there is ISP Special Requirement which is auto set all the VLAN and tag VLAN on the port, when u select the ISP profile, it will told you which port3/4 is for IPTV and VOIP.

Well, my internet connection is using VLAN500 which is for PPPoE connection, which is successful.

Now my IPTV is using VLAN600 which is for TVBOX, the TVBOX system configured pppoe user id and password. I believe its should be using bridge in the port.

After find more info, I understand that my IPTV ISP is using IGMP v3.

And more info I looked at Mikrotik setup here https://wiki.mikrotik.com/wiki/Mikrotik_and_Telekom_Malaysia_UniFi_Setup_Using_QuickSet_-_by_arpee/soonwai

There is no similarity in fortigate GUI.

So anyone have knowledge it this can help? Please enlighten me ya..

Thanks!