Go to the camera setting where the find/inspect is and about half-way down are the pull downs to select main and substream.
Yes, once BI accepts the ONVIF trigger, it will mark those spots on the timeline and in the alerts tab to the left.
These things do need dialing in. Not true plug and play, so do not be discouraged if it doesn't track all the way...trial and error and some guidance from us here can get you on track.
If you haven't put an SD card in the camera, I encourage you to do so, so that you can then playback from the SD card with the IVS rules on so you can see why it stopped tracking. You cannot do that with BI. You can watch the playback in BI, but then you have to guess at what the camera stopped autotracking for. Could be a mailbox, lamp post, shadow, etc., and knowing that can help tweak the system to not stop on those items during a track.