Hello scottj,
Thank you for reaching out to Microsoft Support!
If you have no problem granting permissions, then you need to get tokens through different streams depending on the type of permissions you grant.
Delegated permissions: Use auth code flow to get access tokens
Application permissions: Access tokens are obtained using client credentials flow
Reference document:
https://learn.microsoft.com/en-us/graph/auth-v2-user?tabs=http
https://learn.microsoft.com/en-us/graph/auth-v2-service?tabs=http
Hope this helps.
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