How do I get Cloud Pipelines to authenticate with crg.apkg.io to retrieve the docker images I built?

[NB]

I have created a package registry in bitbucket within the repository that hosts the Dockerfile, and have pushed images with the appropriate semver tags as I've seen fit to do so (in the same way I have done publicly on hub.docker.com)

In my local development environment, I can `docker login` and pull those images fine and, by extension, can use those images in my docker-compose orchestrations.

However, as soon as I use these same images in a bitbucket-pipelines.yml file for any other repository in my workspace, I am receiving an authentication error, presumably because the bitbucket host has no way of... well, authenticating.

What would be the process? The documentation contains no guidance.