Allow apps to use your calendar information
Some apps and websites can use your calendar and reminder information to provide you with services and features. For example, an app might use your calendar to help you set up an event or a reminder.
To authorize an app or a website to use information from your calendar, click OK. If you don’t want to authorize the use of your calendar information, click Don’t Allow.
If you allow third-party apps or websites to use your calendar information, you are subject to their terms and privacy policies and not the Apple Privacy Policy. You should review their terms and privacy policies to understand how they treat and use your information. For more information, see the Apple Privacy Policy.
You can review and change your privacy settings using the Privacy pane of Security & Privacy preferences.
Choose Apple menu > System Preferences, click Security & Privacy, then click Privacy.