Yes, you can set up a guest network w/o portal and with client isolation, but since the EAP is an AP only (not a router!) it just offers functionality to create several SSIDs (one of it you could assign to a guest network), so you will have to handle subnetting and firewalling on a router or using a L3-switch in your network.

See http://forum.tp-link.com/showthread.php?99022-How-to-configure-Multiple-SSIDs-work-with-Multiple-VLANs-based-on-EAP-products for an example on how to set up Multi-SSIDs with VLAN-based subnets to get an idea what's needed for a guest network.