Google SDK
The JThermodynamics web interface is based on the Google Cloud Environment. The Google Cloud SDK has the tools and libraries for interacting with Google Cloud products and services. You can find general instructions on how to set up a Google Cloud environment here. This includes information on how to install other dependent systems such as JAVA and Maven, which is used in the compilation of JThermodyanics.
More specifically, you need to download the Google Cloud SDK for your platform.