I had a similar issue. Make sure that you have all Windows updates that are available. The one thing that was causing it for me, believe it or not, was that I needed to do a clean installation of the latest Studio graphics driver from the NVIDIA website. After doing that and restarting, all was OK.
I did the Windows and NVIDIA update but it didn't change anything....
Which operating system do you have?
Possibly related help articles:
Hello, I have Windows 10.
Hearing more and more reports of this type of thing lately, unfortunately.
If the above suggestions don't work for you, then normally Customer Support recommends this sequence:
1. Uninstall all Adobe apps using standard OS procedures.
2. Download & run the CC Cleaner Tool, remove all apps.
3. Reboot your computer (don't skip this step).
4. Start again from the top by reinstalling the Creative Cloud and your tools.
If still no luck, then the route most people take in this case is to request/use the direct download links for the CC Desktop app or for the 2020 Creative Cloud apps themselves – whatever you need. With those, you can download offline installers which are industry-standard .exe/.dmg files for Windows/macOS.
It is frequently reported those standalone installers will download much faster (and complete!) over the same Internet connection than when using the CC Desktop app... nobody's really sure why.