This is resolved. Our client had to regenerate a different API key for the user. Once that happened, the session endpoint worked. Added the sessionID (along the APIKey) to the downloadURL (which should be https://<your_domain>.my.workfront.com/{downloadURL}). That should work.

Hi @jshaw4 - were you able to get download working? I tried to generate the session based on the documentation `attask/api/v21.0/session` and that call failed with AuthenticationException. Thanks, Chinh