How are users added to an app

[Jeff_Rubenstein]

Do users have to be added through the user tab in the editor? I have users that started using the app wo me having to add their email to the user tab, but all of a sudden I have some users that do not see the app in app sheet using the link I send them unless I also add them to the user tab. But other users do not require this. Anyone of any idea what’s going on?