According to your error message, it seems that an Insufficient privileges issue, and has two solutions to solve it. These two solution can apply depend on different actual situations.
(1) If you only have guest permission in AAD, then meet this error in Azure Devops.
Just go contact the admin to grant the minimum additional permissions to you. For how to grant this, please due to this doc. Let the admin to set Guest user permissions are limited to No. At this time, you will get the minimum additional permissions.
(2) If you are the member of AAD, and just not be authorized to add applications in the directory.
Go User settings, then change Users can register applications to Yes under App registrations section.
Please refer to this section: The user is not authorized to add applications in the directory.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.