Hi,
Firstly, I suggest that you could registry the Windows Store.
Windows key + R, type powershell. Hit Enter.
Copy and paste this:
Get-AppXPackage | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}
into the powershell window and hit enter.
If the issue still insists, you could recreate AUInstallAgent folder. Please check the steps below:
https://windowsreport.com/fix-windows-10-error-code-0x80073cf9/#:~:text=When%20you%20get%20the%20error,process%20again%20or%20cancel%20it.
Reboot to check.
After modifying registry values below:
HKLM\System\CurrentControlSet\Control\FileSystem\NtfsDisableEncryption
It's value has to be set to ZERO.
Hope this helps and please help to accept as Answer if the response is useful.
Best Regards,
Carl