Opening this issue as per the comment here https://github.com/MicrosoftDocs/azure-docs/issues/39330#issuecomment-537108225azure-container-agents-plugin
Doc can be enhanced to discuss about connecting ACR (with or without firewall) with this plugin
Do you need do anything special for ACR comparing with other private registries?
If we can provide one example which uses credentials to pull a image from ACR, That will be fine. If that works with ACR , it should work well with any private container registry as well