Hi @Konrad Wojciechowski (Nokia)
Your account has not enough permissions for scope DeviceManagementServiceConfig.ReadWrite.All
If you'd like to add them to a Custome role, please have a look at:
Device Manage > Set primary user
Choose, change, or remove the primary user of a managed device. This permission must be used in combination with the managed devices read and update permissions.
Also, you can add permissions to an Application for Graph API call, or connect via Powershell
Connect-MgGraph -Scopes "DeviceManagementServiceConfig.ReadWrite.All"
PS It will require to grant permissions with admin account.
Best regards,
Aleksandr
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