The build.deploy.xml file is a convenience build file to create a special jbpm configuration for the jboss application server that will be hosting jbpm. So if you want to use this you have to make sure that the build.properties file contains the proper locations for your jboss installation. The error you get is because the HSQL database could not be started, either because it is already running or because the HSQLDB is not at the expected location, i.e. your jboss home is incorrectly set.
Thank you Koen, now things are getting clearer