I've gotten a temporary solution. We're behind an automatic proxy configuration script, a .pac file, which Adobe Creative Cloud does not understand how to read.
However, we noticed that if I changed it to a static proxy, that is, the IP/hostname and port - it suddenly works. I can now install the CC apps. It's not a permanent solution though because apparently it snaps back after a while due to company policy.
btw, suddenly I can also install Autodesk Fusion 360 aswell!
Perhaps you could try using a static proxy if possible for you.
Regards
- björn