If you cannot create or add new User Account in Windows 11/10 & Add someone else to this PC link is greyed out, not working or does nothing, then see this post.

Learn how to add or remove Remote Desktop users in Windows 11/10 using Settings, Local Users and Groups, PowerShell, and Command Prompt.

As with many aspects of Windows, there are some changes in Windows 8 you need to be familiar with if you want to add and manage user accounts.