According to their information it support onvif so add the camera using the onvif tab. If that do not work add it to NCS using the tab for Custom URL like the other camera from Axis here AXIS M1054 Network Camera - no sound
It supports VoIP and SIP so use that solution for the 2-way audio communication.
Doorbird door cameras are not a classical surveillance cameras using motion detection and more part of a specific entrance security system and needs its own solution. They have this free DoorBird Connect. Have you tested this? I found a lot of interesting things on their site also that it supports onvif.
If onvif do not work and depending on the model test rtsp://username:password@IP/mpeg/media.amp It should give video and possible audio.