This article might be helpful:

https://www.dancovic.com/2025/04/servicenow-cicd-pipeline-for-citizen.html

Hello in this situation who is the admin I need to talk to, as I still can't submit 

same issue here, and I'm using a personal development instance.  I can confirm on a paid servicenow instance I am able to publish the application.

However, I have to point out that the purpose of a developer instance is to develop apps in a full lifecycle.  Why would they hinder it like this?

The main reason for it not working on a PDI is that you only have one instance in a PDI stack and don't have access to push things to the app repo. In a customer instance stack you'll have 3+ instances so there's somewhere for the app to go.

Does this mean I cannot test out the solution in a customer instance where I am using dev and test. The test instance will act as the production instance.