Pay By Group helps groups come together and helps coordinate payments. Once a group completes, however, it's up to the group organizers to send everybody details about the purchase, gift, event, etc. If you want more details on this, you can ask the organizer for them directly.
That said, the "Comment" section on your Pay by Group page still works, and you can use it to communicate with the organizer. It's a great place to coordinate the next steps for your group!