By default, the customer buying the grouped product has free access to all the courses related to that product.
The Admin is now able to decide whether or not the Group Leader will be enrolled by default into the course, irrespective of the licenses purchased.
If this option is checked, the Group Leader can choose to pay for his/her course or buy bulk licenses without enrolling himself/herself in the course.
If you wish to disable group leader access and request payment for his/her access check the Ask Group Leader to pay for course access setting.
This would provide an option to allow the customer to enroll himself as a student in the group and charge for it.