When you click "Buy now," you'll go directly to payment instead of scheduling. Unless the group package also includes 1-1 sessions, clients won't do any booking in a group package. You schedule all the group coaching sessions and clients with this package are automatically invited. 

Explain what makes your group coaching different from 1-1 packages. 
Let clients know how these sessions run, the pre- and post-session work they'll do, and the skills and experience they'll gain from these sessions.