Email Newsletter fail on Upfront/Spirit

Good Day All,
Upfront/Spirit is a delight and even better than I expected! However, the Email Newsletter Signup isn't working.
I have read The Good Support Ticket tutorial.
I have read the tuts.
I set up an Email Newsletter list at MailChimp here:
However, none of the plugins worked.
I posted the issue here:
which confirmed that gravity forms wasn't working with the default field.
I then posted again here:
where I learned that the default field can work if we add the needed information. No where does it say what exactly is needed. Both answers were insightful, but failed to tell me what is missing. Isn't it odd that a no-code theme leaves this out? What do I need to add?
Thank you.