Can I use a VPN with RB50 and which is most suitable?

Alas, Netgear routers do not include the VPN feature you seek.  The only solution is to sign up with a VPN service that provides software for the devices which need it (computers, laptops, tablets, smart phones).  There are plenty of reviews on the internet comparing VPN services.

What Netgear does include in WiFi routers is the ability to create a VPN Host on the router using a version of the open source OpenVPN. https://en.wikipedia.org/wiki/OpenVPN   The purpose is to allow the owner of the system an encrypted pathway to connect to the local network from the internet.  This might be to check on devices running on the LAN or even to manage the WiFi router itself.  This is exact opposite of your goal which is to access internet resources from inside the LAN.