For iCloud calendars, in accordance with Apple Security Policy, you need to set
separate passwords for each app. Follow the steps below to successfully log in.
1. Visit https://appleid.apple.com/
2. Log in with your Apple-ID
(Note: It's a 2 step verification)
3. Once logged in, select ‘Security’ in the side menu
4. Security -> 'Generate password'
5. Enter a label to separate your passwords (e.g. TimeBlocks )
6. Copy the generated password
7. In the iCloud calendar, go to login.
Paste the password to log in.