[2021] CK3 Windows Installer issue

Those errors typically mean the Windows installer/updater processes have a problem. Run the Update app, does it load okay? If so apply anything it finds to fix and reboot.

If that doesn't help, try MS's tool to fix updater issues:

Fix problems that block programs from being installed or removed

The Program Install and Uninstall troubleshooter helps you automatically repair issues when you're blocked from installing or removing programs. support.microsoft.com
Good luck!