To validate a candidate's details and ensure that it is the same candidate appearing for the test, who had signed up initially, then -

1. Click on My Tests tab, and then click on the name of selected test which you shall invite the candidate to take.

2. Click on Advanced Options -> Candidate Registration Fields.

3. In the list displayed, enable the 'Verify' check-box on all the registration fields that you wish to validate from the candidate. 

4. Then click on Done button.

5. Then click on the Share Test button. Enter the name of the new schedule.

6. In front of the Link to share, check the box for Private Access only.

7. Here either manually provide the candidate's email Id and name, or click on Import from Candidates group button -> choose the group(s) to invite the candidate from -> click on Add button.

8. Click on the Done button.

9. Check the box for Send Email Notification and Click on Share link to invite candidates to appear for the test.