Recommendation for VPN Provider

Recently purchased an OrbiRBK853. Attempting to put my HMA VPN service provider on the Orbi. Both Support teams locked up on my inquiry.

What is a compatible VPN provider with Orbi. I am on a Mac platform. I contacted NordVPN and a tech person advised their service is not compatible. Does anyone know if ExpressVPN will work with Orbi or what is the solution for combining a VPN service with Orbi? 

Or do I need to return the Orbi for another Netgear product that is compatible and allows the fastest internet speeds available?

thanks