Hi. For community openvpn we have a nice flowchart for this:

While the concepts are the same, routes are of course added differently in Access Server, but this document about site-to-site routing in AS might help:
Site-to-site VPN routing explained in detail
You might also want to look at the
OpenVPN Cloud service, especially if this is the only use you have for your VPS with Access Server. For Cloud there is this blog article:
Site-to-Site VPNs & OpenVPN Cloud
hth, regards, rob0