The project uses Gradle. Gradle handles dependencies. You need to install Gradle.
The application is written in Java, you need to install a Java Development Kit (JDK). For example OpenJDK (http://openjdk.java.net).
Download the source in archive form from GitHub or install git and clone as
git clone https://github.com/martenlager/SWDev.git
Execute 'gradle build'
The build generates an executable jar in build/libs
Execute 'gradle run' or execute the jar in build/libs
java -jar build/libs/SWDev-{version}.jar
Execute 'gradle test'