Getting started with Fantastical is simple. First, you need to add your calendar accounts in Preferences.
Start by opening Fantastical, clicking the Fantastical menu and choosing Preferences from the menu. You can also access the preferences by clicking on the Fantastical icon in your menu bar, clicking the gear icon in the lower right, and selecting Preferences from the menu.
To add a new account, go to the Accounts pane in Preferences.
Choose the "+" icon at the bottom of the sidebar on the left side of the window to open a panel with account type options:
Select the type of account you'd like to add and click Continue
Fill in the credentials for the account to allow Fantastical to access and sync your events and reminders
Apple requires that iCloud accounts have two-factor authentication enabled in order for apps to connect to iCloud's calendar or mail servers. If you don't have two-factor authentication enabled, enable two-factor authentication on your iCloud account before continuing.
Log in to appleid.apple.com. You'll be asked to enter a verification code from one of your devices.
When you receive the code, enter the digits into the dialog that opens in the browser window
After login is completed, click on "Generate Password..." under the Security section
Give the app-specific password a name of your choosing (e.g. Fantastical)
A dialog will appear with a new password string that you can copy and paste into Fantastical
To add a Google account:
Select the Google account type
Fill in your Google username (email address) and password
Click "Sign In"
Click "Accept" to allow Fantastical to access your calendars
To add an Exchange account:
Select the Exchange account type
Fill in your Exchange email address and password
If you need to enter a username or Exchange URL, you will be prompted after clicking "Add"
Once you've added your Exchange account you can enable delegated or shared calendars by clicking "Manage Delegates..." in the Accounts preferences. See Delegated and shared calendars on Exchange for more information.
If your organization uses Office 365 then add your account as an Office 365 account. If you are having trouble adding your Exchange account and you're not sure if your organization uses Office 365, you can also try logging in to Office 365 with your Exchange email address and password.
If your organization uses Office 365 then it is better to add your account as an Office 365 account rather than an Exchange account. This will allow Fantastical to connect using any single-sign-on or multi-factor authentication methods used by your organization.
To add an Office 365 account:
Select the Office 365 account type
Log in to your Office 365 account
Select the "Other CalDAV Account"
Enter your username, password, and the CalDAV server address