I am under the impression that you can run any version of IBM i Access with any version of IBM i (within reason) and functionality will be the lesser of the two.
Check the website for more info:
From: "Graves, Chuck" <cgraves@xxxxxxxxxxxxxx>
Sender: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>
Date: Tue, 29 Apr 2014 16:02:05
Reply-To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Subject: Client Access & V5R4
Does anyone know what the latest version of Client Access is that I can run on v5r4?
When I click "help/About" in an emulation session, I show "Workstation Program Version 5.9 for Windows"
[Rodda Paint Company!] Chuck Graves
Director of Information Systems
Rodda Paint Co.<http://www.roddapaint.com
6107 N. Marine Drive
Portland, Oregon 97203