The installer (rifInstaller.exe, rifInstaller_linux, or rifInstaller_mac) is built from the source Python scripts using the PyInstaller tool. Full details can be found in the README for the install module.
Follow the instructions on that page for each platform (normally Windows, Linux, and Mac) and gather the the executables for each platform. When you are ready to create a new release, follow the GitHub steps for doing so, and upload the executables to the release when prompted to do so.