You need:

A Docker registry set up for Vault images. See the Vault Cloud Infrastructure guide for information about setting this up

Credentials to authenticate to the Thought Machine Docker registry and client attestations store

If you have not been provided with authentication credentials, email your Thought Machine Client Delivery Manager or representative to request access to our Docker registry and client attestations. Your request will be forwarded to the Thought Machine security team. 

https://docs.thoughtmachine.net/vault-core/4-6/EN/environment_and_installation/infrastructure_docs/infrastructure_and_installation_guides/using_binary_authorisation_and_docker_images/#pulling_docker_images_overview-benefits_of_signing_our_docker_images