Welcome to the Microsoft Q&A forum.
I could not find an official documentation stating the value for <cdn-id>, although I found this informative blog post and in the comments section as quoted you can retrieve de CDN-ID using the value shown in round brackets at the top left of the Edge Cast portal, adding the prefix "80"
. There are other methods mentioned as well in the further comments. Can you please check it out and see if it works?
Please let me know if this resolved your issue and I work with the team in adding this information to our documentation. Thank you!