How to configure the Docker CLI to work with bintray is documented here:
Essentially you give the Docker CLI a username, and a password, where the password value is an API Key from bintray. The API Key is long-lived and can be retrieved using a REST API / https://www.jfrog.com/confluence/display/BT/Bintray+REST+API#BintrayRESTAPI-Entitlements
When one configures Docker CLI with a username and an Bintray API key as the password, the docker cli can pull images from a bintray registry.
However, when one configures a NXRM Docker proxy repo with HTTP auth using the same credentials, then NXRM cannot successfully pull the bintray images.
This is a case where someone using docker CLI can use a bintray remote registry perfectly fine, but NXRM cannot proxy that same registry, even if NXRM has valid username and password values entered in the proxy repo HTTP authentication settings.
Make NXRM Docker proxy repos work using similar configuration (username/accesskey password) as Docker CLI, when pointing at Pro or enterprise bintray repos.