Just a quick one here: the latest plugin step for Pentaho PDI is in the Pentaho Marketplace. So you can simply install it from PDI. Or you can download the zip archive from GitHub, unzip the files and put them in the folder plugin/steps.
The source for the webapp for the rule maintenance is also on GitHub. It can run on a webserver that understands Java servlets, such as e.g. Tomcat. Link: https://github.com/uwegeercken