6 diget number that will coincide with the course you would like to purchase from The Princeton Review https://www.princetonreview.com/medical/mcat-guarantee?ceid=rc-cards-v3
How to Enroll and Get Your Course ID
To enroll in the MCAT Ultimate Course, you'll need choose both a primary and backup Course ID, which identifies the specific class section you're joining. To find your Course ID please navigate to the following link: https://www.princetonreview.com/medical/mcat-ultimate?ceid=nav-gd