Visit the releases page. Precompiled binaries are availabe for x64 Windows, macOS and Linux.
macOS and Linux users
After downloading, you'll probably want to do something like:
$ chmod +x the-downloaded-file
# mv the-downloaded-file /usr/local/bin/mpr (or your preferred location on your PATH)
Building
You'll need go installed (eventually I'll set up CI so you can download a prebuild release). Easiest way of downloading it right now is with go get github.com/marketplacer/mpr