ECS Fargate can not pull from GitLab Registry

When setting up Auto Devops to deploy to ECS Fargate everything works perfectly until the service tries to start and pull down the image hosted in the GitLab registry.

The following error is observed:

CannotPullContainerError: inspect image has been retried 1 time(s): failed to resolve ref "": failed to authorize: failed to fetch anonymous token: unexpected status: 403 Forbidden

The GitLab docs suggest suggest to create a deploy token and add it as the repositoryCredentials parameter in the task definition. See here: Build in deploy works in aws But can't start service

This link is referenced → Private registry authentication for tasks - Amazon Elastic Container Service

However, nowhere does it say what the format of the repositoryCredentials credentialsParameter value is? So, if I have a GitLab deploy token, how can I use it to allow ECS to pull from the GitLab container registry?