Ask HN: How do software platforms ensure money is transferred to lender?

I was wondering how do these platforms that allow businesses to sell their invoice/receivable on them ensure that the lender is paid back? What are the ways in which a software platform can ensure that money is redirected/transferred to the lender who purchased invoice/receivable? Is paper contract the only way to make it legally binding on the borrower to payback or is there some automatic way to redirect money to the lender?