error in Schema registry API using Postman

You might need your credential name added to a role.For reference, you can view the video titled “Get the necessary attribute-based access control permissions”. Start at the 2:40 mark: https://experienceleague.adobe.com/en/docs/experience-platform/landing/platform-apis/api-authentication#get-abac-permissions

Hi @aep_guy  - The mentioned screenshot indicates that this is related to your permission on accessing the AEP component using post API. I would request you to connect with your administrator and have the respective role added in to your account. Admin may add you to the extended developer version for the sandbox that you are trying to create the schema using API's.

Thank you,
Jayakrishnaa P.