From the Airbnb website:
Log in to Airbnb
Access your Airbnb account at www.airbnb.com.Go to the Calendar section
Click on your profile picture (top right corner).
Select Listings and choose the listing for which you want to export the calendar.
Go to the Availability tab within the listing.
Export the iCal calendar
Scroll down to the Calendar Sync section.
Click on Export Calendar.
Copy the link that appears.
From the Check-in Scan website:
Log in to your web dashboard
Access your Check-in Scan account.
Go to the Properties section and click Edit
Navigate to the Properties section and select Edit for the desired property.
Import the iCal calendar
Within the property settings, go to the iCal tab.
Paste the link you copied from Airbnb.
Click on Import iCal.
In a few minutes, your Airbnb reservations will start syncing in the Bookings tab.