By the way, there is a GUI way to install VPN plugins. It's surprisingly hidden though.
Open the Ubuntu/GNOME Software app.
Switch to the Installed tab.
Scroll down to the bottom then scroll up a bit to see the GNOME Control Center app in the System Applications heading. Click it to open the details page for GNOME Control Center.
This page shows the VPN plugins as Add-ons. Check the boxes for the plugins you want installed.
By the way, there is a GUI way to install VPN plugins. It's surprisingly hidden though.
Open the Ubuntu/GNOME Software app.
Switch to the Installed tab.
Scroll down to the bottom then scroll up a bit to see the GNOME Control Center app in the System Applications heading. Click it to open the details page for GNOME Control Center.
This page shows the VPN plugins as Add-ons. Check the boxes for the plugins you want installed.