To better assist you on this, what specific permissions do you have on the resource? Was this working fine or has it been the case since the setup/configuration?
Are you referring to any specific Azure docs for the steps? Analyze video and audio files with Azure Media Services
Just to highlight, you must assign Azure roles to your app to manage Azure resource as per this doc. Assign Azure roles using the Azure portal and you may wish to know - Azure AD roles and Azure roles are two different roles, see this doc: Differences between Azure roles and Azure AD roles
If the issue still persists, please provide more information on the specific steps you are taking and the exact error messages you are receiving. This will help us to better understand the issue and provide more targeted assistance.
Note: Kindly do not share any PII data on the public forum,