For the source code .tar.gz, click here
or
mkdir -p uxp && wget -O uxp/uxp-2019-06-12.tgz https://github.com/ronsorlabsoss/xulrunner-win32/releases/download/2019.06.12/uxp-2019-06-12.tgz
This AppImage is for Linux64 platforms. We don't support 32-bit Linux.