You can easily claim a receipt once the ad has been closed. Remember that you need to be logged in to your account:
1. Open the app and click "Activities" in the bottom dark area
2. Choose ad
3. Scroll to the bottom and press "Get receipt"
Keep in mind that Tiptapp is a platform connecting private persons.
This means an advertisers receipt wont include VAT as the pick-up is done by another private persons.
A helpers receipt will include VAT on the 20% fee that Tiptapp charges for the use of the platform.