: You must submit a research proposal via the ResearchDataGov portal .

: Use the NLS Investigator User's Guide to learn how to search by "Area of Interest" rather than keyword. Accessing Data | National Longitudinal Surveys

: Excellent for browsing thousands of variables and creating custom datasets without needing an account to just explore.

The query appears to refer to the restricted-use Zip-Code data files for the year 2021 (often referred to in survey cycles as "2021" or "Round 29/30" data). Overview of NLSY79 Zip-Code Data