You can configure your database connection as part of the Crowd Setup Wizard. It will make things easier if you have created the database and deployed the database driver before you start.
HSQLDB database is supplied for evaluation purposes
The Crowd distribution (not EAR-WAR) is shipped with an embedded HSQLDB database. You can choose this embedded database during the Crowd setup process. The embedded database is fine for evaluation purposes, but for production installations you should connect Crowd to an enterprise database. This also lets you take advantage of existing database backup and recovery procedures.
Select the page corresponding to your database, for help on setting up an external database: