Just wanted to share in case it helps some others. Long-time user and remember the incredibly challenging "suite" installs.
So through CC and CC 2014 I actually, slowly, began trusting the cloud update "app" screen and letting it update my programs without much concern or thought.
I was aware the CC 2015 uninstalled 2014 so I did not think twice about checking that box.
However like many, upon clicking in the cloud desktop app to update a program to CC2015, it would hang at some percent either during the extraction or install. They would not go to completion.
One suggestion was to go to the direct download links and download from there. It also said I had to be logged into my cloud account while I did that. I did that and went to the link. I then got some kind of message saying I was "forbidden" to access that folder on the server. Hmmmm......
Then after more research.....the suggestion was to uninstall and reinstall the CC desktop app. However....that also failed because it said another installer was running (of course with all those failed attempts). So I stopped any process I could find that smelled like an install/setup EXE or adobe product running. No joy.
So I then rebooted and was then able to run the uninstall and re-install process. That allowed me to get the new adobe cloud desktop installed and then my programs installed just fine.
Nothing new above. However by putting the sequence together and the attempted and successful solutions together, hopefully it can help someone out....and hopefully whatever went wrong with CC2015's update/desktop app gets fixed before the next round of updates. I know the desktop app was updated because every time you run the thing it would tell you it needed to be updated.
Also, I saw some older threads about the slow "welcome" screens. I have a very fast internet connection and PC....and they are still very slow and turned them off.
The good news is things now seem to work!