You can use the Bulk Ordering feature to allow allow customers to order multiple items by entering a quantity.
Log in to Kickflip and open your product.
Click on the blue + button and under 'Select an input type', pick Bulk order and hit Create.
The quantity field will be displayed in your customizer.
Setting a minimum or maximum order quantity
Select your Bulk order question.
In the right side panel, click on the cog icon.
Under Quantity settings, enter your minimum and or maximum quantities.
Offering quantity-based bulk pricing discounts
You can set a bulk pricing discount if you want the price per item to decrease as the quantity of purchased items increases.