looks like you don't have access to this notebook yet
Copy the link from an already existing Onenote Page, Section or Onenote and select Copy Link.
Attempt to pasting the url to Onenote by adding a Onenote tab/paste link (returns "looks like you don't have access to this notebook yet" with a Request Access button.
Clicking request access just takes you to the sharepoint site where you can open the Onenote
Selecting the option in Sharepoint to create a link (allowing everyone in my organization to edit) and then pasting into Teams gives me the message that the document needs to be hosted on Sharepoint (which it is).