This documentation was tested on fresh installs of Ubuntu Desktop 18.04.1, 20.04 and 22.04.1.

Install the NetworkManager OpenVPN plugin if you don't have it. To do that, open Terminal and type:
sudo apt-get install network-manager-openvpn-gnome

• Generate and download an OpenVPN configuration file: My account > Services: VPN > "Generate OpenVPN configuration file" > "Generate"
• Open Settings and click on “Network”. Click on the + icon next to “VPN”.
• Choose “Import from file…”. Select the arethusa.ovpn file you just downloaded and click “Open”.
• In the “Identity” tab, enter your VPN username and password, then click “Add”.

Click on the Network icon in the status bar then “VPN” > “Connect” or “arethusa”.

Once connected, check your IP addresses.

The OpenVPN log is in /var/log/syslog , mixed with all other system logs. Skip until you see lines with openvpn.