Follow the below steps to shortlist the candidate:

1. Go to the test analytics/report whose candidate you want to shortlist.
2. Click on the "Funnel" option present in the left vertical menu.
3. Click on "Submissions".
4. Select the candidates to whom you want to shortlist.
5. Then click on the "Mark as Shortlisted" option to shortlist all the selected candidates.
6. Or you can also shortlist the candidates while viewing their performance report by selecting the "Mark Shortlisted" under the "Action" option present on the top right corner of the page.
7. All the shortlisted candidates will be reflected under the "Shortlisted" tab.