Question: how to install odk briefcase?
Answer: Download the ODK Briefcase JAR file from GitHub. [+] show details. Some browsers may warn that JAR files might harm your computer. ... 
Double-click the downloaded JAR file or, from the command line, run java -jar {path/to/ODK-Briefcase-vX.Y.Z.jar} [+] show details. ... 
Follow the instructions to start using Briefcase.