This is for the new MacBooks, correct? Is that what you have? It also requires that you are running El Capitan and have an Apple Multi-port Adapter. Not sure from the article that you need the update if you are running Sierra. My MacBook has Sierra so I have opted to ignore this update because I would not have any need for it at this time.
Did you try the instructions to Verify that the update got installed? If so, what was reported? Did you follow all of the pre-installation instructions including the connection of the power cable from the adapter to the power adapter/source? This prompt you mentioned, is that the one at the end for Restarting the computer? Or the one at the beginning for starting the installation?
Apple doesn't post articles here in user posts. You have to do that. That is precisely why I had no idea what your problem was. Now, I do.