Many use their existing NVR as the POE switch and bring the cameras in from the NVR.
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, in BI 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.
OR if all your cameras are connected to a POE switch, as long as you have an extra open port, you can connect the switch to the BI computer and bring in each camera separately via esch IP address.