Select the listing you'd like to generate an iCal for, on your Uplisting calendar
Open the 'booking sites' tab on the property settings
Go to 9Flats (assuming you don't use 9Flats already)
Enter the word 9flats.com on step one and click next
The second step will show the iCAL link for the property
Exit without completing the second step
The iCal link that you will get from the steps provided above is the Uplisting iCal link for that listing.