The payment tweet says one thing but the payment fees portal has TWO sections stating that it will be a receipt upload and that if you paid upfront you'd get a refund IF you don't meet the cap in time (which we all knew as we paid for it). I'd certainly trust the official payment fees website rather than one tweet (the intention of the tweet is so people pay when their application is ready to submit, but it doesn't mean you did something wrong by paying beforehand, you're just risking waiting for a refund IF you don't get a spot or aren't eligible.