The difference between an Exhibition Challenge and other challenges is what happens once it ends:
For Exhibition challenges, photos are selected to be Printed or Digitally displayed in an art space (i.e. Photo Fair, Art Fair, Art Gallery).
Photos that appear in these Exhibitions have a chance of being sold and you receive the earnings.
*Important: You must complete the application form prior to the challenge end.
The application form refers to the payment fee.
Once the payment has been completed, there is no other form to fill in :)