If your house does not appraise for the selling price, usually there are three options.
No. 1 The buyers can raise their down payment by the difference of their current down payment and the difference in the appraisal. i.e. Selling Price $200,000 Appraisal $190,000. Buyer adds $10,000 to Down Payment.
No. 2 The Seller can take less. In the above example the seller can accept $190,000.
No. 3 Buyers and Sellers can split the difference. This does not mean they must split 50-50.
No. 4 SOMETIMES (in the past-before banking changes by this administration) the Seller can carry a note for whatever difference Buyer and Seller can agree on.
That's 4. But there are others. My list includes the most common ways to overcome a low appraisal.