Logging in as an admin
If you created your own DayBack Online account you're already an administrator and clicking on "Settings" in the calendar's left hand side bar will reveal an "Administrator Settings" button that will let you configure sources.
If you're logging in to our demo using "firstname.lastname@example.org" you're not an admin of that account and won't be able to configure a the FileMaker connection there. (We wouldn't want you publishing your FileMaker events to all our demo users.) You can create your own account here: https://app.dayback.com/#/sign-up
Finally, if someone invited you to join their DayBack group they can decide to make you an admin of the group or not: ask them nicely.