I am looking to start using my VPN service with my Vero 4k+ devices. As an extreme novice to linux, I am not sure where to start and hoping someone may be able to provide some guidance. I have read from the VPN support site, there are 4 options for installing on Linux based systems, but again, need some help picking one and maybe some pointers to potential issues. The link to their site is https://protonvpn.com/support/linux-vpn-setup/.
Any help is greatly appreciated.
Thank you.
Seems that ProtonVPN is not supported by this addon 
Anyone how to use ProtonVPN on OSMC ?
You need to download the configuration files (see How to download Proton VPN OpenVPN configuration files - Proton VPN Support), then point to them in vpnmanager setup (use User Defined provider). I have noticed using the protonvpn config files as is, my dns may be leaked (identified by running dnsleak), but a quick web search shows how to fix by adding an additional line in the config files (using any text editor; How To Fix DNS leak with OpenVPN - VPNInsights). I download multiple config files (some using secure core some without), as some do not always connect. Hope this helps.
I have used it successfully for years, but honestly have moved to LibreElec as I am able to use use wireguard which is faster (OpenVPN vs. WireGuard - Proton VPN Blog). I am not aware if this is possible in osmc, but vpnmanager does work.
Forget my comment about using “block-outside-dns”, as I didn’t realize this is only valid for Windows.
Also, forgot to mention I needed to delete the following lines from my ovpm files to get VPNManager to work (as there is no such directory in kodi):
up /etc/openvpn/update-resolv-conf
down /etc/openvpn/update-resolv-conf
Lame question…how ? Sorry this is embarrassing 
Open VPNManager
Under “VPN Configuration”, select " Click here to update VPN settings"
“VPN Provider” = User Defined
“User name” and “Password” = obtain by going to protonvpn.com, logging in, going to Account, then look under “OpenVPN / IKEv2 username”.
Select “User Defined import wizard”
Under the dialog choose to select either Files or Directory. I download multiple ovpn files from ProtonVPN and save them to their own directory, and so use that option. After selecting the option, choose the files or directory.
You should be prompted with “Update the ovpn files to best guess…”, I choose Yes. Then prompted about renaming, again I choose Yes.
Finally under " VPN Connections I set the first provider to one of the imported ovpn files to auto start on Kodi startup.
Remember that you need to delete the lines from the downloaded ProtonVPN ovpn files as I mentioned previously.
I already have VPNManager installed, and so provided directions to update settings. On first install of the program, you may be presented with the setup wizard and so the fliw may differ slightly, but same concepts.
Regarding dnsleak, I updated my network settings to Manual (as opposed to dhcp), then set my DNS Server to 1.1.1.1 (these settings should be configurable in the osmc configuration program).
Previously it was set to my ISP provided modem address, which caused the dnsleak program to show my ISP servers. After updating, dnsleak still says I’m leaking, but now I only see the ProtonVPN servers.