I'm afraid you haven't given any any useful information at all so there is no way to help. It's like saying "Something has happened - explain it!".
Did you try more than once? Does it do this every time you try? Might it have been a problem with your payment method? Have you checked with your bank in case they declined the transaction? Tried an alternative payment menthod if you have one? Could a temporary internet failure have interfered with the encrypted connection?
As mentioned by the previous user, we will need a bit more info to be able to pinpoint what might've caused this. We want to help so here's a few we can try to eliminate:
We want to help get this fixed. We don't want to keep your granddaughter from enjoying the world of VR and becoming a member of the Oculus family.