SYNC ALL DATA IN OUTLOOK CALENDAR

Hello, and hope you have a great day. Currently, I am developing an Appointment Scheduling System. There is a feature I need to add. The feature is to sync previous appointments in the client Outlook Calendar into the system.

I am stuck in finding a package or reference to sync the Microsoft Outlook Calendar into my Code Igniter 3. Please advise the keyword to google.

Thank you so much in advance for helping me out.