Overview
An error is being received when trying to test a newly created API:
Client is not authorized to access "API URL". You need to create a "client-grant" associated to this API
Cause
The Application is missing authorization, but the linked documentation addresses client grants, not API authorization settings.
Solution
The client is most likely not authorized. This can be corrected by going to Applications > API > Management API > Machine to Machine Applications in the tenant dashboard.