I was also receiving the error message "This isn't a valid iCal URL – please try again." I read the previous comment and, because I am not listed on any other platforms, I copied my ABB link and pasted into a Word document. I then copied it from Word and pasted into Booking.com. It worked!
I was also receiving the error message "This isn't a valid iCal URL – please try again." I read the previous comment and, because I am not listed on any other platforms, I copied my ABB link and pasted into a Word document. I then copied it from Word and pasted into Booking.com. It worked!