Install ProtonVPN app

To install ProtonVPN app
From synaptic install:
protonvpn-stable-release

As root run:
     

Code:

apt-get update && apt-get install proton-vpn-gnome-desktop


reboot

The following is necessary for Mate and Xfce only:
From synaptic install:
network-manager-gnome

Remove  connman, connman-gtk and connman-ui

Add /usr/bin/nm-applet to Startup Applications
reboot

The previous three steps could probably be done first, an expert can correct me if I’m wrong  and I usually am  

Connect to the internet through network-manager, you can now setup and connect to ProtonVPN with network-manager or connect with ProtonVPN app