As part of the enterprise plan, you're able to only allow users from certain countries to enter.
In this example, only users from United States, Canada, United Kingdom, and Australia will be allowed to enter. If someone is trying to enter from another country, it will give them a message saying it's not allowed in their region.
Furthermore, you can select the "Check If Allowed Worldwide" checkbox to allow anyone to enter.
Note: the checkbox is selected by default with anything less than the premium plan.