The ruling on one who appointed a person to sell an item for cash but he sold it on installments

A woman appointed another woman to sell her jewelry and said to her: "Sell it for this price, and whatever is more is yours." The other woman sold it on installments without the owner's permission, and paid her friend the price she had specified to keep the rest for herself. Is there riba in this?
Answer: If the owner permits the sale on installments, there is no harm; otherwise, there is harm, because she did not authorize her to sell on installments. She only ordered her to sell for a specific amount, with any surplus belonging to the agent. If she permits the sale on installments, there is no blame in that, because the right is hers.
The presenter: May Allah reward you with good. If she paid the price in advance and she received the value on installments.
The Shaykh: If she sold it for a price that is partly immediate and partly deferred, by saying to her: "Sell it for ten thousand," and she sold it for ten thousand immediate and three or four thousand deferred, then the surplus is hers.
The presenter: The surplus is for the seller?
The Shaykh: For the selling agent, because she did not harm the principal. The money the principal requested was given to her, and she obtained it, which is ten thousand, for example.
So the point is: if the requirement of the authorizing principal is fulfilled, the surplus is for the agent. Yes.
The presenter: Very well, may Allah reward you with good.