Hi ​@ConciergeCFO - Thanks for reaching out!

If the Appointment Schedule calendar is listed as a sub-calendar, you should be able to select this from your Availability page here: https://calendly.com/app/availability/calendar_settings
 

For reference, I have a few different sub-calendars, so my options look like this:
 

This article can walk you through creating any new calendars for Calendly to check under your main account. You can read more on this here: https://support.google.com/calendar/answer/37095?hl=en

Keep in mind, Calendly will check for any events listed as Busy, and mark those as conflicts. Events marked as Free will be ignored, and allow for events to be booked over those times.

Let me know if you have any questions!