May I know whether you had checked whether the ports and URL are not blocked on network firewall ??
If yes, just for confirmation purpose , try downloading CC apps from direct download link and check :
Adobe CC 2015 Direct Download Links: Creative Cloud 2015 Release | ProDesignTools
If you get Access Denied Error while downloading follow below steps :
Step 1)
Click on the below link and open Photoshop Elements download link.
Note: We are not downloading anything from the Photoshop Elements page.
Do not close the page , simply keep it open.
Download Photoshop Elements products | 13, 12, 11, 10
Step 2)
Once the page is opened , try downloading the Apps which were prompting Access Denied error :
http://prodesigntools.com/adobe-cc-2015-direct-download-links.html