To send the Teams link via Email or SMS, first, the users need to link their teams to the Appointments in iinsight from Menu > Appointments > Click on the share button then click "Grant" and login via Teams credentials. Once granted, you'll see the option "Revoke"
While creating an Appointment, please select the Location "Online" and click "Create a Teams Meeting" to link the appointment with teams and schedule meetings on teams.
The reminder/confirmation message should include the variable {APPOINTMENTADDRESS} as a placeholder for the Teams meeting.
The message can be customized from Options > System Reminders/KPI > Appointment Reminders > Select Reminder/Confirmation under SMS/Emails, The message can be customized and variable inserted.
Please Note: You'll need to set MS integration to link Teams to Calendar, please see the below article on how to set the MS integration