In Step 5 in the instructions it says "Select the User you want to act as". By default krisv is selected. If you do not toggle between david/krisv then the following stack trace is seen

12:52:42,758 ERROR [org.drools.persistence.SingleSessionCommandService] (Thread-75) Could not commit session: org.jbpm.workflow.instance.WorkflowRuntimeException: [HelpDeskService:1 - Gateway:11] – XOR split could not find at least one valid outgoing connection for split Gateway
at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:130) [jbpm-flow-5.3.0.Final.jar:5.3.0.Final]
at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerNodeInstance(NodeInstanceImpl.java:205) [jbpm-flow-5.3.0.Final.jar:5.3.0.Final]
at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:164) [jbpm-flow-5.3.0.Final.jar:5.3.0.Final]
at org.jbpm.workflow.instance.impl.ExtendedNodeInstanceImpl.triggerCompleted(ExtendedNodeInstanceImpl.java:47

It would be clearer if either the instructions made it clear that you must toggle or the drop down is a blank user to start with. It also doesn't say whether you need to click the submit button or not.