Hello,
OpenVPN Access Server makes configuration for the OpenVPN daemons by using settings on the admin UI and command line. It does not have a server.conf that you can manually edit. You can try putting manual entries into the 'server config directive overrides' field in Advanced VPN in the admin UI. But I am pretty sure that client-connect and client-disconnect are unsupported directives for OpenVPN Access Server.
If you need something to happen when a client connects, post-auth scripting can be used on Access Server to achieve something similar.
https://openvpn.net/vpn-server-resources/post-auth-programming-notes-and-examples/
Kind regards,
Johan