No, that is the correct size.
after installing design Extender, when you start Dreamweaver, it will launch the WebAssist installer which download the rest of the design extender files.
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.