Basically, zone rules define default policies for incoming/outgoing network traffic and packets forwarded to other zones for specific network interface or a collection of interfaces. This differs from the general settings in that general settings set default policies for the traffic, which is undefined in zones settings. Zones allow for logical segmentation of different traffic types, which provides more flexibility for traffic management.
Based on your zones table, forwarding in both directions openvpn->LAN and LAN->openvpn is allowed, which it should be.