After successfully registering for an event, you will receive select notifications about your tournament. Tournament reminders, bracket links, and match start/check-in now notifications will be automatically enabled for your profile for every tournament. Mainline Notifications Settings are located under the My Settings --> Notifications tab. 

Under your notifications tab, you will be able to change the notifications that you receive when competing in a tournament. You can opt into receiving SMS notifications by adding a phone number, or adjust which notifications you wish to receive when competing in tournaments. Currently, notifications settings are Mainline wide, and not tournament-specific, so be sure to leave on any important notifications.