Users are setup in, you guessed it, the “Users” section of the WP Admin.
There are different levels of user access that can be assigned (aka User Roles).
Best practice is to have two Administrators so that if one gets locked out of the site, the other can unlock them in a worst case scenario.
The primary Administrator for this site uses the email: [email protected]
It will be up to the primary Administrator to create additional users as they deem necessary.
Learn more about each user role and what they get access to on the WPBeginners Blog article, “Beginner’s Guide to WordPress User Roles and Permissions“.