Only supported if the ArcGIS Portal has access to the agency's map services.
Requires an ArcGIS 10.4+ Print Service.
The printing service must have access to the services users want to print. If services are hosted on a local intranet server, users cannot use the Print function provided in ArcGIS Online. Users must use a local service instead.
How To Set Up Web Map Printing
Copy or write down the ArcGIS Print Service REST URL.
If the service is secured, check the Service is Secure? box. The program will use the credentails associated with the first service listed on the Map Services tab.