Coaches can view a student's artifacts by navigating to the Portfolio Coach tab located on the left navigation pane in VSTAR.
Then click on the drop-down and select Students.
Find the student with an artifact you wish to view and click on their name: 
Then select Artifacts from the drop-down:
Now to view the artifact you want, you can either click on the title of the file to the left, or the download icon to the right: 