before installing the WebAssist extensions, you need update the extension manager, then install the Database & Server Behaviors add-on:
https://creative.adobe.com/addons/products/1315
Once that is installed, open DW then Close it, and then install the WebAssist extensions using the extension manager. The updated extension manager will show access points to manage DW CC and another to manage DW CC 2014, make sure you select to install the WebAssist extensions into DW CC 2014.
After installing the extensions to DW CC 2014, Open DW and a PHP page top trigger the WebAssist installer.