The Dropbox tool allows you to set up folders where students can turn in assignments online. TurnItIn's plagiarism detection service is integrated with D2L's Dropbox tool, so you can get originality reports for student's files within the Dropbox folder. You can also set up your Dropbox folder so that you can grade files within it and have your feedback automatically transfer to D2L's Grades area.
Can I create a Dropbox folder for group projects?
Yes. First you have to set up the student groups in your course (see the Groups page), then when you create the dropbox folder, select the Group Submission folder setting (see the Creating Dropboxes page). With a group submission Dropbox folder, all students in the group will be able to see the feedback you enter for the assignment, and the score you enter in the Dropbox grading interface will be transferred to the Grades area for all of the students in the group.