The event is postponed. From the Greenday website
The Hella Mega Tour show originally scheduled for August 13, 2020, has been postponed. We are working with Green Day, Fall Out Boy and Weezer to identify a new show date at Wrigley Field and will provide updates as they become available. Tickets will be valid for the new show date.
If the show ends up being cancelled you will receive a refund/voucher. If the event is rescheduled your tickets will be good for the new date.