How i can add product (for example with 10 qty) to quote if this product has 0 stock qty.
You can enable backorders for this product.
To reach this you should make product qty - 0, click on the
Advanced Inventory, set
Out-of-Stock Threshold to your needed qty, and set
Allow Qty Bellow 0
In case you place the order with 10 qty of this product, product's Salable Quantity will be -10.