To try it out:

On this page,press the green button named "Code". A dialog pops down.
Select "Download Zip."

On your computer, extract the content of the downloaded Zip file into a folder, 
creating a folder with the same name as the Zip file but without the Zip extension.

cd into the newly created directory and type

java -jar target/fide-1.0-SNAPSHOT.jar 

Under Windows, assuming you downloaded to "Downloads" you type something like
32-bit Java: "\Program Files (x86)\Java\jre1.8.0_333\bin"\java.exe -jar Downloads\fide-master\fide-master\target\fide-1.0-SNAPSHOT.jar"

64-bit Java: "\Program Files\Java\jre1.8.0_333\bin"\java.exe -jar Downloads\fide-master\fide-master\target\fide-1.0-SNAPSHOT.jar"

If your Java version differs from mine, you have to adapt the commands above.