This error message appears when you try to query or create new datasets when no project has been selected. You must query and select data within a project.
A similar error message.
Access Denied: Project bigquery-public-data: User does not have bigquery.datasets.create permission in project bigquery-public-data.
if you accidentally try to query while browsing BigQuery public data.
If you try to create a database in google bigquery public data you may also run into this issue.