annual leave destination - free tickets
There is nothing to do with the interviews! It depends on which town/city you are from!
You have to give them your annual leave destination and you get the tickets from there to Dubai. All the connecting flights are paid by the company. If there is no direct Emirates flight, they use other airlines they have agreement with.
Make sure, your annual leave destination is correct in your contract: you won't be able to change if for 3 years.