Windows: Simply install the the Windows-Installer package (.MSI-file).
If it shows a DLL missing error, you need to additionally install the MS Visual C++ Redistributable Package
from here. See also
this.
Mac/Linux: Install Python 3.11 (or newer) for your platform,
then install MTGProxyPrinter via pipx or pip: pipx install MTGProxyPrinter.
The launcher will be named "mtg-proxy-printer".