Adobe customer serivce doesn't care that Cloud sign-in doesn't work

Creative Cloud works for 15 million subscribers.  If it's not working on your system, don't be so quick to dismiss professional advice until you try it. This could indeed be a Windows issue. Did you try installing Creative Cloud on another computer?

It might actually BE a Windows issue, especially if you have the 2004 update to Windows 10. Something in that update broke things with the Windows Credential Manager, which can in turn affect your ability to stay logged in to the Creative Cloud. The latest release of Windows 10 (2H20) might fix it, but I haven't heard one way or the other.

Here's an article about the issue along with some troubleshooting information. (There will be lots more if you search for Windows 10 2004 Credential Manager issues.) 

https://www.windowslatest.com/2020/08/11/windows-10-may-2020-update-breaks-down-critical-feature/

make sure your os is up-to-date and then suspend all av, antimalware, firewalls and other software that can affect your internet connection.

test if you're still getting signed out.  if you are and that occurs immediately (as soon as you sign in making it impossible to open any adobe apps, start with the lines beneath the asterix (*):

if you're able to sign in for a minute or longer and then are signed out, something is still active on your computer causing problems.  you can check your oobe folder** to monitor your cached adobe credentials to see if they're being deleted or changed.

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first try, resetting the cc app: To reset the Creative Cloud desktop app, make sure it's in the foreground, then press:

Win: Ctrl + Alt + R
Mac: Cmd + Opt + R

if that fails, try to repair
https://helpx.adobe.com/download-install/kb/creative-cloud-install-stuck.html

if that fails go ahead and uninstall/reinstall per the above link

if that fails, do a clean cc install following each applicable step:

uninstall every cc app including preferences, https://helpx.adobe.com/creative-cloud/help/uninstall-remove-app.html
then uninstall the cc desktop app, https://helpx.adobe.com/creative-cloud/help/uninstall-creative-cloud-desktop-app.html
clean your computer of cc files per http://www.adobe.com/support/contact/cscleanertool.html
check for, and if available, update your os
restart your computer (don't skip this)
reinstall the cc desktop app, https://creative.adobe.com/products/creative-cloud.
if you're unable to install the cc desktop app at this stage, use an administrator account (solution 4 here, https://helpx.adobe.com/creative-cloud/kb/creative-cloud-missing-damaged.html)
use the desktop app to install your cc programs/trials

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something on your computer is causing the problem removing/changing your stored credentials (eg, av, antimalware, cleaner), or you have a permissions issue storing your sign in credentials.

to check/confirm look for file changes in your oobe folder (esp, the opm.db file) where your credentials should be stored and not changed unless you explicitly change your adobe id and/or password.

A) Mac OS: /Users//Library/Application Support/Adobe/OOBE
NOTE: \Users\\Library\ is hidden by default. To unhide see below***

B) Windows: C:\Users\\AppData\Local\Adobe\OOBE
NOTE: AppData (and its subfolders) is hidden with Windows default settings. To unhide see below***

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see bottom of https://helpx.adobe.com/creative-cloud/kb/unknown-server-error-launching-cc.html for info on unhidding folders