If you are an administrator on the site and already have a login to login as administrator of the site you will not have a separate login to log in in as a reviewer, you will use your same login that you login with as an administrator.
When you first login and are on your Home Dashboard, from that dashboard you will click the Review Applicants Icon. Once you click on this icon you will then be directed to the Review Applicants page.
(If you have been assigned applicants to review and you do not see this icon on your Home dashboard please contact the Global Administrator for assistance with having this icon added.)