There are two options, either via the Grade Centre or via the Course Tools menu. Using the Course Tools menu you can also access Direct Submit. If you select Safe Assign items you will see an overview of Safe Assign items in this course and with View Submissions you can access the submissions.
The overview of submission shows only students that have actually submitted.
Download all submissions or check an individual submission. To make use of the Inline Grading option you have to access each submission individually.
You can also download submissions via the Grade Centre
Search for the appropriate column. You can either download all submissions or open an individual submission.