Overview
Whenever a non-admin user runs an external query, there may be a chance of running into unauthorized issues saying "Not authorized to use external query"
Applies to
dremio-enterprise-20.1 and above
Any external source - for example, MySQL
Details and Cause
In SQL Runner, we can see this error:PERMISSION ERROR: Not authorized to use external query. 
Solution
Provide the "External Query" permission to the affected user.
Log into Dremio as an admin user, look up the affected user, and enable the "External Query" privilege.
Save.
Test the change by logging out as the Dremio Admin user - then log in as the affected user.
Run the external query that failed earlier, for example:
select * from table(Mysql.external_query('select * From mysql.db'))
This time, the query runs fine.
Resources: