By default this container does not contain the database for Dolibarr. You need to use either an existing database or a database container.
The Dolibarr setup wizard (should appear on first run) allows connecting to an existing MySQL/MariaDB or PostgreSQL database. You can also link a database container, e. g. --link my-mysql:mysql, and then use mysql as the database host on setup. More info is in the docker-compose section.