Hello Mahesh Kurucheti,
Thank you for reaching out to Microsoft!!
For the error mentioned while trying to access transcripts using Graph API,
Did you create and assign an application access policy? This is a requirement when using application permissions, as detailed in the documentation:
To use application permission for this API, tenant administrators must create an application access policy and grant it to a user. It authorizes the app configured in the policy to fetch online meetings or online meeting artifacts on behalf of that user (with the user ID specified in the request path). For more information, see allow applications to access online meetings on behalf of a user.
Hope this helps.
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