If you are setting up a new Automation with the Automatic Action: 'Schedule a meeting using Calendly', you will see that you need to enter your Calendly calendar link.
To find this URL, simply go to your Calendly account and look for your calendar. It should look something like this:
Once you've located your calendar link, simply click 'Copy Link'.
Note: You will need to own a free Calendly account in order to move forward with this. You can sign up for this here.
From here, navigate to Automations > select 'New Automation'. Next, update the Trigger and Automatic Action to 'Schedule a meeting via Calendly'. Here you can paste the link under 'Calendly URL':