The No Refunds policy completely undermines your idea. If users cannot negotiate or return the money after payments, it is a suitable place for fraudsters, as any file can be uploaded, and when the brother party buys this file, he finds that it is incorrect or a wrong file, and then he cannot demand money or even money. Negative rating on the seller.
In short, your paid service is more like payment API and not Sell Files Securely for Cryptocurrency.
No Refunds
At Filesity, all sales are final. We do not provide refunds for any purchases made on our platform. The primary reason for this policy is that sellers receive funds instantly in their cryptocurrency wallets upon a successful transaction. This immediate transfer means we cannot retrieve or reverse the funds once they've been sent.