The difference between the EPR and EAR, do I need both for an air-gapped environment?

Hello,

Sorry if this is a dumb question but I am new to setting up Elastic and hosting my own package registry. When using Elastic Agent do I need to have both the Elastic package registry and artifact registry to be hosted on a server or just one of the registries. My main issue is getting the Elastic Agent to be able to access the integrations as there is an error when finding agent integrations. I guess I am more confused about how downloading the integrations look like.

For example:
https://epr.elastic.co/search?package=synthetics&prerelease=true&kibana.version=8.13.4 (This is the error)

The error is due to the VM not having external internet access, so what I did was redirect it to my own hosted registry where kibana-8.13.4-x86_64.rpm exist, yet I still get the same error. I am now unsure where I am going wrong, is that the wrong kibana package.

I did follow these resources:
Air-gapped environments | Fleet and Elastic Agent Guide [8.13] | Elastic
Installing in an air-gapped environment | Elastic Installation and Upgrade Guide [8.13] | Elastic

Kind Regards,