Login to ads manager; Select " Traffic" or " Website clicks"; In website url section put event link e.g., https://www.facebook.com/events/xxxxxxxxxxxxx/;
Login to ads manager
Select " Traffic" or " Website clicks"
In website url section put event link e.g., https://www.facebook.com/events/xxxxxxxxxxxxx/
This will activate "Get Tickets" option in "Call to action" window.