Can I set up a VPN connection using IKEv2 instead of IKEv1?

Yes, you can. The goal of the NAP VPN connection screen is to make it ridiculously simple to set up VPN. Each one of our customers has a dedicated Fortigate firewall protecting their private cloud. Customization is possible, but must be done from the native Fortigate firewall interface. Note that you do not have access to manage the firewall from the native interface until the account is upgraded from trial to a paid plan.