Hi ahl26,
We see you're having some issues signing into iCloud on your PC, and we'd like to see if we can help get that resolved.
Please try signing into the iCloud website here, just to see if the issue is prevalent across the device, or just in the app: iCloud
Do you have any other devices, such as an iPhone, iPad, or Mac, that you could try seeing if you're able to sign in there? Also, be sure that the PC is also meeting the requirements laid out here: System requirements for iCloud
That'll include checking for any Windows updates, ensuring you're using the latest iCloud for Windows software, amongst other items.
If you happen to be using any kind of firewalls, antivirus, VPNs, or other security/networking software, please try disabling or uninstalling them for the moment. Sometimes there can be conflicts, and that'll just help to rule those out.
Take care.