When students in a group need to submit their work they should go to the assignment and click on Submission in the tab bar. If the assignment is open for submission and groups are enabled, the student will be able to add group members to their submission.
When students click the input field in the Group Members card a dropdown will show with students in the class that have not yet submitted. If the students have previously worked together in a group the group members will appear at the top of the list.
When the work is submitted you will see a preview with information about their submission. If the submission period is still open all students in the group can change or delete the submission.