User management option will help you specify the groups of users who will be able to use your app, e.g. setting various levels of access to an app. Find this button in the left part of editor menu. By default, there are the following types of users: anonymous, logged in and app reviewer. You can add more types, click on “Add new type” button and enter the needed types. In case you want to remove the types you entered, click on red cross to the right from type title.
Read more in our User manual here