The extension can not be installed
..it requires Dreamweaver version 9 or greater. Mine is 20.2. last version of Extension manager. Installing , reinstalling, restarting....
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.