I reached out to Apple Developer Support and they directed me to the forums.
This video "Explore Retention Messaging in App Store Connect" shows a "Retention Messaging" section at the 3:21 timestamp of the video, within "Subscriptions" below the "Billing Grace Period" section.
For the apps in our account, there is no "Retention Messaging" section available within the Subscriptions area.
I am not asking about the API. I do not believe the API is required in order to have the Retention Messaging section show up in App Store Connect.
In the video, the speaker says “I'll share an overview of Retention Messaging, and how to set it up in App Store Connect” and she shows how to navigate there.
While she explains that “Real-time Retention Messaging is powered by the Retention Messaging API” - she also says that you can “create the same views using real-time Retention Messaging as you can when using retention messages in App Store Connect.”
Is there something that we need to do in order to get access to this area of App Store Connect so we can set up Retention Messaging? Thank you so much.