WebGoat 5.4 is mainly a bug-fix release.
WebGoat installation instructions
WebGoat 5.4 Standard:The standard release is a download, unzip, and click-to-run release. It comes with the Java Runtime Environment and a configured Tomcat 7 server. There are versions for 32 bit Windows and Ubuntu.
WebGoat 5.4 Developer :As of version 5.3, WebGoat now uses maven. See the readme file for instructions on how to build and setup an eclipse environment.