If Social Networking is enabled, you will notice a dynamic summary indicating the number of users who have created a profile and download your event app.
If you have the permission set to Users Must be Known to the Event or Approved by an Admin, you will notice a red alert icon. The number next to the Menu Item with an alert, is the sum of users pending approval or the number of pending posts. In the example below, there are 15 users pending approval.
To approve the pending users, simply click on the Menu Items with the alert. After approval is granted, the users will have access to all of the social features.