The Fortress Core requires an LDAP server to store its information. Its other components, Web and Rest, require a Java Servlet container. This page includes some links on getting started.
The Core is used by the other components, Realm, Rest and Web. These are to install ApacheDS or OpenLDAP (pick one), and configure for usage. For rapid deployment, you can skip the APACHEDS and SLAPD quickstarts, and use one for DOCKER instead.
Apache Tomcat is used for the Fortress Rest and Web deployment testing.
The Realm plugs into Tomcat and provides JavaEE security support.
Next, pull either Fortress Web or Rest binaries from Maven, run inside Tomcat instance.
More info can be found from each of the projects README's.