Helo Jeremy,
The organization ID is usually shared with you via welcome email during the provisioning. If you provide me with your hostname, I can check the ID from my end as well. Please feel free to use the DM for that if needed.
I am just little bit concerned about the documentation that you are following as per this article was written for our GD Platform customers. As far as I know, you are working with GD Cloud. May I know what are you trying to achieve here, please?
Do you plan to set your own custom OIDC?