As Rugged relied on Orekit for the frames computation, Orekit must be properly initialized for Rugged to run.
The simplest way to configure is to first retrieve the example orekit-data-master.zip file from Rugged download page, available in the Rugged project download page (Get the physical data) and to unzip it anywhere you want, rename the orekit-data-master folder that will be created into orekit-data and add the following lines at the start of your program (before Orekit is called for the first time):
File orekitData = new File("/path/to/the/folder/orekit-data");
DataProvidersManager.getInstance().addProvider(new DirectoryCrawler(orekitData));
This is sufficient to start working.
Note that some of the data in the orekit-data-master folder needs to be updated, typically the UTC-TAI history file, which is updated about once every 18 months by IERS, and the files in the Earth-Orientation-Parameters folder which are updated regularly by IERS. The update frequency depends on which file you use.
The data provided in the example archive from Rugged site are example only and are not kept up to date. The real operational data are live, and remain under the responsibility of the user.