Can't upload my ebook to Apple Books via PC

I'm trying to upload my book to Apple Books. I'm using my PC windows 10.

I am following these instructions:

https://itunespartner.apple.com/books/articles/how-to-publish-an-ebook-from-the-web-3108

I am literally at step 1: https://authors.apple.com/epub-upload/start

I have the option Choose how to publish: "Submit a New Book" which I press (Continue is grayed out).

When I try and press "submit" I get as far as a message: "To publish to Apple Books, your Apple ID must be associated with a content provider ..." and it says to set up Users and Roles in iTunes Connect, then try again.

BUT I can't get through this step. 1. In the User Roles, I'm admin and it doesn't seem I can check anything else. I thought it was the tax or bank information, but I have just recently finished that portion.

Any ideas? I suspect there's something else missing, but the error messages are pointing me to the wrong issue I think.