Not able to sync Apple Calendar

What I did:
During 1st instance I did not grant access of my calendar to Agenda.
What happened:
While try to “connect to calendar” second time, I was take to systme preferences / firewall option.
What I expected:
I was expecting grant access window to come up so that I can sync my calendar to Agenda

Things that might be helpful to know (Agenda version, OS and model, etc):
Agenda version: 1.3
OS: Mac OS 10.13.3
Model : MacBook Air

I have a feeling this is a restriction placed by Apple. If you refuse permission the first time, we are not able to request again to use the calendar. It will just refuse and fail.

So instead, we send you to the system preferences, where you are able to update the setting there.

Kind regards,
Drew

There is no way to update the setting from system preference as much as I know. Even if I disable the firewall. It would still land me on the system preference page again. I dont get any option to enable sync of calendar there.

You need to go to Security & Privacy in System Preferences. Select the Privacy tab, and select Calendars. Make sure you check the box for Agenda.