You need to expose a new scope within your dox42 Online App in order to select API permissions of “SharePoint Online Extensibility Web Application Principal”.
Steps
Open the Microsoft Entra admin center: https://entra.microsoft.com
Go to App registrations and select the entry dox42 Online.
Select the Expose an API tab.
Expose an API tab
Select Add a scope.
If you have not set an Application ID URI, you will see a prompt to enter one. Enter your application ID URI or use the one provided. Example:
https://<yourcompany.com>/fb04c99e-.....
).Important
The Application ID URI must be globally unique.
When the Edit a scope dialog appears, enter your scope's information:
Edit a scope dialog
Select Save and continue.
Result
You exposed a new scope within your dox42 Online App in order to grant API permissions to “SharePoint Online Extensibility Web Application Principal”.