The KEPServerTroubleshootingTool-extension:1.2.0 is included with the ThingWorx Manufacturing Apps. I assume you are working with the Manufacturing Apps, is that correct? If not, please see this page for more information on how to obtain and install these apps:
In order to work with the Demo Data Set and Simulator Learning Lab, it will be necessary to use either the Dev Kit installer option, or the licensed ThingWorx Platform with the Manufacturing Apps extension option. You will not be able to use this Simulator tutorial with the Express/Freemium install option.
Please let us know if this information points you in the right direction toward getting this issue resolved.