Here you go download the zip folder at the bottom of this post extracted to your desktop, open the Clock folder.
Put the 2 highlighted in red 1 Clock folder and 1 Clock.theme file in C:\Windows\Resources\Themes
Open the green highlighted Basic folder
Put the 1 highlighted in green 1 Clock.theme file in C:\Windows\Resources\Ease of Access Themes
It will show up in Personalization as Clock in both Installed Theme and Basic and High Contrast Theme.