Can't Use "MariaDB" Windows User/Group Account To Give MariaDB Permission To Access Data Folder

I am trying to upgrade my aging 10.3 MariaDB database and have followed the guide steps of uninstalling the old version, installing the new version (10.6) and copying the needed data and ini files to the new folder location; Copying the "data" folder from the previous 10.3 installation folder to the new 10.6 installation folder.
Subsequently, the new instance of MariaDB isn't able to access this data folder due to folder permissions.

Checking on the differences between the copied "data" folder permissions and the original "data" folder that was created by the 10.6 installation, I find there is an entry listed as "MariaDB" in the list of Group and user names. The strange thing is, I can't find, let alone add, this user/group to the "data" folder that I'm copying over from my old 10.3 location.

What is this Windows user group?
I am not able to find any documentation by MariaDB or any guides where to find or add this user group.
The only mention I found of this is in https://stackoverflow.com/a/69981074/9162516

> ... this "group user" is not create under Windows "users and groups".
> So you cannot add this group on security tab and set permission to
> another folder.

What the hell? How am I supposed to assign the permissions to the data folder from an older version or if I want to copy the folder from an external source that doesn't have that user group permission already set on that folder and its contents?

Google search results is sending me unrelated guides creating MariaDB database user accounts.

There is no MariaDB user or group on Windows, never was. The service is running under so-called service-account NT SERVICE\servicename user, in 10.6 . The service is running under "NETWORK SERVICE" in the older versions.

(It is not hard to check, Run services.msc => find name your service => right "Properties" => Log On)

That user, that runs the service, needs full access to files in data directory. How do you you grant permissions, either with command-line tools like icacls, or clicking in Explorer, is up to you.

Now, if you did not remove the data directory in 10.6, and just copied the contents of your old datadir, you'd be fine. That's because on Windows, the permissions are inherited from parent directory, and they were correct already.