To set up meetings and integrate your calendar, navigate in HubSpot Sales to Settings. On the left, select Sales > Meetings.
Next, select the option Connect your calendar. Choose the calendar program that corresponds to your email: Google Calendar or Outlook 365. To check if your email provider is compatible with meetings, refer to this article.
Finally, when prompted, select Allow in order to give meetings access to your calendar.
Once you have completed setting up the integration, the meetings tool will automatically prevent clients from booking meetings during any events that are set to show as Busy on your integrated calendar. This helps prevent double bookings from occurring, and you never need to bother with letting a prospect know the windows of time you are free.
Please note: if you have enabled the Google Calendar two-way integration with HubSpot, when you create a calendar event with a contact directly in Google Calendar, the event will sync to the CRM as a meeting engagement. With this two-way integration, meetings created through the Schedule tab on a contact record in the CRM will send actual calendar event invitations to the contact. Without your calendar connected, it will strictly just create a meeting engagement on the record. This two-way integration is not available for Office 365.