Outlook - Open Shared Calendars in Outlook Mobile App Open your Outlook app on your smartphone. If you do not have the Outlook app, please download the app and follow the steps below. Select the calendar option in the app. Open the the calendar menu. Tap the add calendar button. Tap Add Shared Calendars. Search for the person or group whose calendar you already have permission to access Tap the add button next to their name. The calendar will appear in your list.