Once you've successfully enrolled a group member in a course, he's ready to log into his own account and begin coursework at his convenience.
To view the group member's username, click on your My Group tab, and click on the individual's name under My Group Members. That group member's information will expand, showing his username:
To reiterate, group members do not take their courses while logged into your group administrator account. Rather, each group member logs into his/her own individual account to complete coursework.