You can ask … nicely … the folks at EncryptMe. They are, via grandfathering, supporting a few users with older macOS machines, but I don't know if they have any interest in adding new users to that small number.
I would recommend encrypt.me for a paid VPN. They have iOS and macOS apps and the service is $100/year. The apps let you indicate trusted networks and if you are not on a trusted network the apps will automatically enable the VPN. I have been using it for a couple years now and it just works.