Facebook Marketplace always claim they pay sellers within 5 days of the date customers receive their orders. However, that is further from the truth. They pay weeks later and when they do pay sellers, its never the amount that you are supposed to receive.
They pay in spurts - meaning: if they owe you $100, you might get $10 within 4 weeks. That's how they operate their marketplace. I have been waiting weeks to get paid my money and have not received a dime of it yet.