@Alex Mang You need to configure Application permissions and not delegated permissions. If you decode the token at https://jwt.ms, you should see the 'Directory.Read.All' and 'Directory.ReadWrite.All' permissions are Roles, not as SCP (Scope). As per my testing on https://github.com/azure-ad-b2c/graph-api, both 'Directory.Read.All' and 'Directory.ReadWrite.All' are required.
In this case, we are fetching the audit logs in application context as the token we are using to make the graph call is issued to the application. Delegated permissions are used when the application has to perform certain actions on behalf of the user. Selecting Directory.AccessAsUser.All delegated permission is used when the the application has to impersonate the user for accessing directory data. I don't think this will help you fetching the audit logs specific to that user. Using this sample all audit logs will be exported to JSON format, you can then filter the logs to fetch logs specific to the required user.
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