In order to receive capacity warnings or notification of reaching a capacity in a room, here are the steps you will need to take:
Only Administrators can receive a notification, you may need to adjust the security level of users needing to receive the texts and emails.
To set up notifications, go to Setup - Users and select the user you would like to receive capacity notifications. Their account will need to have a phone number and/or email address, depending on how you would like them to receive the notifications. Then, check the box that says "May we send text messages to this phone?". Lastly, click Save User. This admin should now receive notifications when classrooms are reaching capacity, so long as the rooms have been set up to send alerts.
To learn how to set up a room's capacity level, click here.
Please note: There may be a 1-2 minute delay for text messages to be received.