Invalid WNS credentials when setting up Azure Notification Hubs with UWP app

I have been following these instructions to set up Azure Notification Hubs with my UWP app: https://video2.skills-academy.com/en-us/azure/notification-hubs/notification-hubs-windows-store-dotnet-get-started-wns-push-notification

• I have used a personal (outlook.com) email with Partner Center
• When I click on "app registration portal" it instead takes me to this page, instead of directly to Azure as the instructions indicate:
• I clicked "Add an app in the Azure portal" and logged in with the personal account (which is a global administrator in the directory)
• I added a new registration for "Personal Microsoft accounts only", as the instruction doc indicated.
• I added a secret and copied these values across to the Azure Notification Hubs:
  • Package SID: ms-app://[Package SID from Partner Center]
  • Security Key: [Secret Value of app registration]
• When I click Save, I get this error:

Error updating notification hub

{"error":{"code":"BadRequest","message":"Invalid WNS credentials."}}

I have checked all the instructions in the doc, and don't see why this isn't working, so any help would be much appreciated!