FactoryTalk Users and Windows-Linked Users are created in the FactoryTalk Local Directory.
The easiest way to do this in FactoryTalk View Studio is to navigate down the project tree to the bottom, and click on the System folder, then Users and Groups, then Users.
Right-click on the Users folder to add a new FactoryTalk User.
Once you're using FactoryTalk Users, you need to pay more attention to managing the FactoryTalk Local Directory. If you end up Restoring a project archive and over-writing your Local Directory, you'll end up corrupting all of your User accounts.
I can't seem to avoid this, so I make a point of writing down all the Users and Passwords for each project so I can easily re-create them later if I mess up.