The role you should assign is AcrPull because it specifically grants the ability to pull (download) images from the Azure Container Registry, which is the required permission for the user. Assigning the Reader role would provide broader access than necessary, as it includes permissions beyond image pulling. Similarly, assigning the Contributor role would grant excessive privileges, as it includes permissions for creating, deleting, and modifying resources, which are not required for simply downloading images. The AcrDelete role is also not suitable, as it specifically grants permission to delete image data from the registry, which is not needed for the task described. Therefore, AcrPull is the most appropriate role that meets the requirement of allowing image downloading without granting unnecessary privileges.
https://learn.microsoft.com/bs-latn-ba/azure/container-registry/container-registry-roles?tabs=azure-cli