ECS to Authenticate with Docker Hub

I'm having issues authenticating with a private repo in docker hub from my AWS EC2 instance.

AWS provides documentation on how to set this up. http://docs.aws.amazon.com/AmazonECS/latest/developerguide/private-auth.html

I've followed the documentation and am still getting the following error:

Error response from daemon: repository user/reponame not found: does not exist or no pull access

I've created an ecs.config in the /etc/ecs directory

my ecs.config (Note: I've removed my credentials)

ECS_ENGINE_AUTH_TYPE=docker ECS_ENGINE_AUTH_DATA={"https://index.docker.io/v1/":{"username":"username","password":"password","email":"fakeemail@gmail.com"}}

I then stopped and restarted ecs service.

I still get

Error response from daemon: repository user/reponame not found: does not exist or no pull access

Note: I am able to log in manually using docker login from my linux ec2 instance, then pull from my private repo