I got the same issue with a 3.8 fresh install on 10.11.1
I removed it via the directions on Apples site, restarted, then reinstalled it, restarted again, same thing happened.
I changed the "Would you like to customize?" to "No" and I still got the same message.
When I went to install it from the app store it was only 18M so I don't know if that was missing anything.
I am on a iMac27 i7(4X3.5Gh) with 16G RAM, 512 SSD (Bootcamp even split)
I did all this to try to get around, whatever the issue is with not being able to use Screen Sharing over messages to remotely connect to a client with issues. Messages refuses to connect with anything but text. No audio, Video, or SS, when over the internet, with any other Mac, at all. However FaceTime does appear to work. This is overall getting very frustrating.