What does this mean?
It means you're trying to access data with a third-party application that has not been authorized at the account level. You'll need to ask the institution admins to grant your application more permissions.
Permissions are, at the lowest level, granted based on your user role. For instance, if you're a student in a course, you cannot use the API to access the gradebook for the whole course. Developer Keys work the same way, having scopes enabled and disabled for specific purposes.
Retrieving data ...