Initial Setting
(If not shown correctly, please sign into your iCloud account . The due date data will be stored in your iCloud private database.)
https://gyazo.com/83102834262116673a7d05340f628497
Press the above "+" button 1.
https://gyazo.com/be2150303d0299f6be5dde4aea72e4b6
Click "OK" to access your calendar.
https://gyazo.com/cb3cd58567f90456204fecfaff550290
Click "Allow" to receive notifications from the App.