Revit 2016 subscription extensions are not currently available at the Revit Exchange (coming soon), however they are available for download from your Autodesk Account. Follow the following steps to obtain your Revit 2016 Subscription Extentions.
2. Navigate to the Product updates & select the extension for the product
3. Download the exe file and double click to install
4. Open Revit 2016 to check that the Extensions Tab has now been added