Does the download error pops up when you try to install it or after the installation?
If possible please post a screenshot.
I can't speak for Michael, but I'm seeing the same thing on a MacBook Air (running an El Capitan / OS X 10.11 beta):
The error message comes up on the CC Desktop's "Apps" tab. Where it *should* show the Apps in your CC package (I've got the Photo package, so this should show Lightroom and Photoshop), it's got this error message. Just to be safe, I uninstalled CC Desktop, re-downloaded it, and reinstalled -- and got the same error dialog again.
I believe you are getting the 'Download error' in the Apps panel.
Please refer to the help document below:
You may also refer to the threads below: