Fatal Error

When I try to activate this plugin I get an error that reads:

Plugin could not be activated because it triggered a fatal error.

Fatal error: Class ‘Ai1ec_Exception’ not found in /home/alzheimerist13/public_html/wp-content/plugins/all-in-one-event-calendar/all-in-one-event-calendar.php on line 27

https://www.ads-software.com/plugins/all-in-one-event-calendar/