Answer
This is caused by the JFrog Artifactory user account used for the install not having 'Deploy/cache' privileges on the relevant Docker repository — without that permission, the install can authenticate to the registry but is rejected when it needs to cache a Docker-Hub-proxied image (like a calico/node image) locally. Confirm and correct the Artifactory user's Deploy/cache permissions on the relevant repository, and open a support case if the issue persists after that's corrected.