Apple News is not letting me to verify National Geographic subscription

I don’t have Apple News Plus, but I have a National Geographic subscription directly with that organisation. I have been to that channel through Apple News and would like to link the account for ease of access, but Apple News says it is having trouble verifying the account. Is there a way it will recognise my subscription?

[Re-Titled by Moderator]

Original Title: i have a National Geographic Subscription. Apple News will not let me verify this subscriptio