Yes, you seemed to have the correct setup in your GSC to BigQuery for the bulk export. The Unknown error failed for unknown reasons, all you need to do is to retry for another export and revisit your setup and check the following:
Check again the IAM permission, it should have the editor and owner permission, then it should ask you to grant the permission. GCS and BQ should have the correct permissions and roles
Check your dataset, your dataset seems to be okay
Dataset location seems to be okay also
If issues still persist, you can reach out to Google Cloud Support to deeply investigate your account and provide guidance.