If the Access Server itself can reach the target network, then giving access using NAT should also work.
If the Access Server itself can NOT reach the target network, fix that first. A beginner's mistake we sometimes see is that people configure the subnet they want to reach as a subnet for the VPN clients themselves to use. That's a conflict. Fix that by making sure the subnets for the VPN clients themselves are unique.
There's also a useful debugging guide here:
https://docs.openvpn.net/troubleshooting/troubleshooting-reaching-systems-over-the-vpn-tunnel/