Thanks for reaching out. You won't be able to use the Persistent Derived Table feature in Looker if your database is running in read-only mode. Looker requires the ability to write to the database for this feature.
You can still execute regular or 'Ephemeral' Derived Tables that get will be injected as a WITH statement at run time. Follow the instructions here for GRANTing the right privileges to the Looker user to enable regular tables.