Questions you need to answer to receive better help... please answer as much as you can, that relates to your problem, back in your original message
If a program is not showing on the Cloud screen, it is most likely because your computer does not meet the specifications
FOR EXAMPLE, Premiere Pro requires a 64bit computer - Not all apps displayed for download | Creative Cloud desktop app, Adobe Application Manager
What error message do you see, or what is the screen you see that does not work? (examples... a BLANK login screen, or a spinning wheel)
A screen shot works well to SHOW people what you are doing - http://forums.adobe.com/thread/592070?tstart=30 for screen shot instructions
Are you using Windows or Mac, and exactly which version? (include "dot" numbers like Windows 8.1 or Mac 10.9.3)
Which brand and version web browser are you using... and have you tried a different web browser?
What Firewall do you use, and have you tried turning it off to download?
What anti-virus do you use, and have you tried turning it off to download?
Has this ever worked before? If yes, do you recall any changes you made to the program, such as adding Plug-ins, etc.?
Did you make any changes to your system, such as updating hardware, printers or drivers; or installing/uninstalling any programs since this last worked?
Are you using an account with Administrator Privileges? Run as Administrator will sometimes help (this EXAMPLE http://forums.adobe.com/thread/969395 is for Encore + "All" Premiere)
What were you doing when the problem occurred?
What other software are you running?
Tell us about your computer hardware. How much RAM is installed? How much free space is on your system (C:) drive?
Hardware Blue Screen shutdowns http://forums.adobe.com/thread/1427408?tstart=0
For Windows, do NOT rely on Windows Update to have current driver information
(you need to go direct to the vendor web site and check updates for yourself)
What is your exact brand/model graphics adapter (ATI or nVidia or ???)
What is your exact graphics adapter driver version?
Have you gone to the vendor web site to check for a newer driver?
ATI Driver Autodetect http://support.amd.com/en-us/download/auto-detect-tool
nVidia Driver Downloads http://www.nvidia.com/Download/index.aspx?lang=en-us
Do you have dual graphics adapters? (common in many "energy saving" laptops)
-Use BIOS http://forums.adobe.com/thread/1019004?tstart=0
-link to why http://forums.adobe.com/message/4685328
-and a Mac Utility http://forums.adobe.com/thread/1017891?tstart=0
JUST FOR MAC USERS
Next link says After Effects, but check YOUR permissions !!!
-Mac 10.9.4 and OpenCL issue https://forums.adobe.com/thread/1514717
Mac 10.9.3 workaround https://forums.adobe.com/thread/1489922
-more Mac 10.9.3 https://forums.adobe.com/thread/1491469
-Mac 10.9.3 and CS6 https://forums.adobe.com/thread/1480238
Enable Mac Root User https://forums.adobe.com/thread/1156604
-more Root User http://forums.adobe.com/thread/879931
-and more root user http://forums.adobe.com/thread/940869?tstart=0
Case sensitive hard drive
Troubleshooting guide for Mac freeze
-next link says After Effects, but check YOUR permissions !!!
Some links concerning error codes
A12... download & install error http://forums.adobe.com/thread/1289484
-more A12... discussion http://forums.adobe.com/thread/1045283?tstart=0
U44.. update error http://forums.adobe.com/thread/1289956 may help
-more U44.. discussion http://forums.adobe.com/thread/1275963
-including DW039 https://forums.adobe.com/thread/1500609
Errors 201 & 205 & 206 & 207 or several U43 errors
Sign Out When Sign In http://forums.adobe.com/thread/1450581?tstart=0 may help
-and 'looping' https://forums.adobe.com/thread/1504792
BLANK Cloud Screen http://forums.adobe.com/message/5484303 may help
-and step by step http://forums.adobe.com/thread/1440508?tstart=0
Mac Spinning Wheel https://forums.adobe.com/message/5470608
-Similar in Windows https://forums.adobe.com/message/5853430