How does a delegate schedule a Teams meeting in Outlook?

Hi EdwardLee,

Generally, when someone gives you the delegate permission of their calendar, you will receive an email notification about this, you can click the Accept button in the notification email to add this shared calendar to your calendar list. See below picture (I was tested this in the Outlook web app (OWA), so I will share detailed steps regarding the OWA side):  

When the shared calendar get successfully added to your calendar list, click View Calendar: 

Then go to the calendar view and click New event, in the "Search for a room or location" field, you need to click Teams meeting firstly. Then select the delegator's calendar from the drop-down list in the upper left corner, add meeting details and attendees, click send:

As for the Outlook desktop client, you can simply click the “Open this calendar” button from the sharing notification email and then click New Teams meeting icon to schedule the Teams meeting for the delegator. For more details, here are some articles for your reference: 

• Open another person's Exchange Calendar
• Schedule a Teams meeting from Outlook (Note: make sure to select the delegator's calendar when you schedule a team meeting)

Best regards,

Jennifer