readthedocs getting started page instructs to add nsidc-daacdata as authorized Earthdata app. However, searching Earthdata authorized apps, I don't see this one.
Has it perhaps changed names?
Earthdata authorized apps that include 'nsidc' in their title (link to search): NSIDC DAAC Earthdata Drive, NSIDC Landing Page Prototype, NSIDC V0 OPeNDAP