And because the question is certain to arise again, and so instructions are on the group archive, here are step-by-step instructions for adding OneCore Voices to Windows 10 . . .
Adding Additional OneCore Voices to Windows 10:
1. Settings, Time & Language, Speech Pane
2. Navigate to the Manage Voices Grouping, Add Voices button and activate.
3. The Voice packages dialog opens and the first thing in it is a search box that allows you to enter the language you're looking for. It's a good idea to enter something here as it makes the list that you select from that follows focused on that language and its dialects.
4. There will be a checkbox for each language/dialect, check the one(s) for the voices(s) you want.
5. Activate the Add button and the voices you have chosen will be added under Windows 10 for any program(s) that can use them. How you select those voices is specific to the program in which they are being selected, and should be documented in that program's user guide.--
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
Always remember others may hate you but those who hate you don't win unless you hate them. And then you destroy yourself.
~ Richard M. Nixon