You should be able to still use Extension Manager for versions before Dreameaver CC 2015. Adobe just dropped support for the Extension Manager for CC 2015 and future versions of 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.