If you already have access to X-Road Test Service's testService service, the fastest and easiest way to try out the application is to download the executable jar version (x-road-test-client-0.0.8.jar), copy settings.properties and clients.properties configuration files in the same directory (specified by the system property propertiesDirectory), modify the default configuration (Security Server or X-Road Test Service URL/IP: settings.properties => proxy.url) and finally run the jar:
java -jar -DpropertiesDirectory=/my/custom/path x-road-test-client-0.0.8.jar