Download the ZIP file from the ES3C3 web page. Right-click on it and “Extract all”. Select a suitable location for the files to extract to, for instance H:/Year_3/ES3C3 and it will create an Engine_balance folder.
Start Matlab.
Use the folder address bar and/or "Current folder" window to navigate into this folder, so you can see the list of its m-files in the folder window. Choose the app you want to run (long_balance.m, fr_masses.m or balancing_app.m), click on the file and press F7 to run it (or just type the file name, without the “ m”, in the command window).