When adding Navient Loans, Quicken accepts Username and Password. It then presents a popup for SSN, followed by another popup for DOB, but there is no popup for last name. (Last Name is required for Navient on [Removed], and as per the thread above on the Mac version of Quicken.)
This answer for Quicken on Mac does not work on windows since each field is presented in a separate popup:
https://community.quicken.com/discussion/7883532/navient-loan-account-not-linking