This command worked for me on Debian to install DarkMX:

cd /tmp;wget https://download.darkmx.app/darkmx-1.23-linux64.deb -O darkmx.deb && sudo dpkg -i darkmx.deb && sudo apt install -f;whereis darkmx

up to date download link can be found at https://darkmx.app/

Yes, using the system deb packager via the mouse-submenu and the operation is reduced to two mouse clicks.

Using a browser to download https://download.darkmx.app/darkmx-1.23-linux64.deb

Then in the folder that darkmx .deb file is downloaded into, highlight that file, right mouse click to bring up the sub-menu selections and choose Open With GDebi Package Installer. It checks to make sure your platform OS dependencies for DarkMx are installed and installs the DarkMX package.