1. Decide how you want reps to work with attendees. From Setup, configure Lightning Sync for Microsoft Exchange or Google, selecting the appropriate sync directions.
2. From Setup, add the Attendees field to the Event page layout or the quick actions layout for events.
3. Tell reps that they have to create and edit events from Lightning Experience, the Salesforce app, or their Microsoft Outlook® or Google Calendar™. If reps create or edit records in Salesforce Classic, they can’t work with the attendees field and events don’t sync.Invitations initiated in Lightning Experience or the Salesforce app are emailed from Microsoft or Google Calendar. Attendees can accept or decline event invitations from those email or calendar applications only. Attendee responses then sync to Salesforce so that other attendees can see the attendance status.