Not clear if that's current or all-time enrollments. 2M current IS enrollments would be wild, so I'm guessing it's all-time, and since IS isn't admission/semester-based, it's probably counting each individual class as an enrollment.
BYU (Provo) probably has > 2M total classes enrolled in the last 7 years.
30K students * 5 classes/student/semester * 2 semesters/year = 300K classes/year