Map Download Failed. Unable to download the map. Empty username/password

Error Message

Adding an Esri basemap for offline use from Portal for ArcGIS to Collector for ArcGIS returns the error:

Error:  
Map Download Failed. Unable to download the map. Empty username/password

Note:
The functionalities of ArcGIS Collector, ArcGIS Explorer, and ArcGIS Tracker are now available in ArcGIS Field Maps. There are no new capabilities planned for these apps—all future updates will be focused on Field Maps. Migration is recommended. See ArcGIS Blog: Migrate to Field Maps for more information.

Cause

The following are possible causes for this issue.

• Esri basemaps are not configured for offline usage by default.
• An incorrect Esri basemap service URL is referenced. The service URL is referencing https://services.arcgisonline.com/rest/services, which is the root directory for ArcGIS Online services, which allows navigation of listed services, resources and associated operations in ArcGIS Online. However, it does not provide the option for maps to be downloaded for offline usage.

Solution or Workaround

Depending on the cause, follow the instruction listed below.

Note:
To use an Esri basemap with a Portal for ArcGIS map offline, an account which is part of an organization in ArcGIS Online, Portal 10.2.2 for ArcGIS or later, and ArcGIS 10.2.2 for Server or later are required.

• Configure the Esri basemap for offline usage. The following Collector for ArcGIS document describes how to do this: Prepare maps on Portal for ArcGIS.
• Add the layer as a basemap using the Use as Basemap option in Portal for ArcGIS. The following Portal for ArcGIS document describes the steps to do this: Use your own basemap.