I hope you reached out to Jack and got the answer you were looking for here prior to your event. Just in case anyone has the same question in the future, I'll go ahead and answer it here now. Everyone that will be driving at a Track Night event needs to create their own account and profile on TrackNightinAmerica.com to register. They can then elect to register in the appropriate run group. If not driving, it's not required that your guests register unless there are specific instructions on the event page instructing them to do so.
Hope you had a great time!