Hello,
The
NOT_AUTHORIZED error occurs when the user authenticating the request is not authorized to perform this operation. Only users with
Administrative access can accept and reject manager account link requests. Could you check the access level of the email address used to generate the refresh token?
You will be able to login in to the manager account, navigate to the Tools icon > Account access tab > Users. This will contain user's email address with their access level. Let me know if you have any questions.
Regards,
Bharani, Google Ads API Team

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