In BI, you select add camera and put the IP address of the NVR into the IP address location. Put in username and password and hit find/inspect and let BI do its thing.
Then about halfway down is a pull down for Camera number and pick camera 1 and then hit ok. The camera should show up. Then add camera and the select copy and copy this camera and then change the number 1 to a 2 and repeat for your cameras.
OR depending on your NVR, it may populate all the cameras in the main and substream pulldown boxes and you just select a camera number and then add another camera and select the next pulldown.