Launch the MySQL monitor:

mysql -u root -p

Create the database for the Druid and Superset metastore:

CREATE DATABASE druid DEFAULT CHARACTER SET utf8;
CREATE DATABASE superset DEFAULT CHARACTER SET utf8;

Create druid and superset user accounts, replacing the last string with your password:

CREATE USER 'druid'@'%' IDENTIFIED BY '9oNio)ex1ndL';
CREATE USER 'superset'@'%' IDENTIFIED BY '9oNio)ex1ndL';

Assign privileges to the druid account:

GRANT ALL PRIVILEGES ON *.* TO 'druid'@'%' WITH GRANT OPTION;
GRANT ALL PRIVILEGES ON *.* TO 'superset'@'%' WITH GRANT OPTION;

Commit the operation:

commit;