Excellent. This will be interesting.
See figure below.
0.ONVIF only works on LAN so you must have the camera on the same LAN as the computer.
1.add a new camera
2.use the tab ONVIF Source
3.click on Browse to find the source. If it is not there write the IP number in the field Unknow/Custom.
5.click on Get Profiles. Now in the field ONVIF Profiles there should be one or more choices that you can select depending on what the camera can deliver. Select one and click on 7.
If everything is fine you should see the video from the camera. ONVIF is a standard, but it is not always that the manufacturers blow that to a 100%, but for video it is usually no problems.
When this is working you can go back to this configuration, but this time go to the tab Custom URL. There you can see the exact URL that the is used for the communication. That is very interesting to have here in the forum.
Good luck and please report back how it goes,