after you install the extensions in the extension manager, when you open Dreamweaver, open a PHP page, this should trigger the WebAssist installer to finish installing the extensions.
after the installer completes, make sure to restart Dreamweaver.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.