I'm a bit confused as to whether you understand what you should be using to install your extensions, but the easiest way to install at the moment is by using the Extension Manager from DMXZone.com. This handles all of the installs and updates for extensions from DMXZone automatically, but you have to install other vendor extensions manually by dragging from your desktop on to the DMXZone EM... but ensure you have chosen the correct version of DW from the dropdown before though.
Works a treat for me.
Adobe's EM is a dead duck for anything CC2015. You now have to go through their exchange and they take a cut. A bit like Apple's business model for iTunes, which effectively will only increase the cost of the software third party vendors will create in order to recoup the lost revenue paid for Adobe's cut.