Typically the quantity is set on the PayPal pages. It's available by default for Add to Cart buttons. For Buy Now buttons, you'll want to make sure the "Do you want to let your customer change order quantities?" is set to yes under Step 3 of the button creator.
After the customer clicks an Add to Cart or Buy Now button, they'll have the option to change the quantity on that PayPal page.
That's the easiest way to do it. If you want to allow them to set the quantity on your website before clicking the button, you can use the quantity variable and forward that information to PayPal. You would need to add a custom line of code to the PayPal button code. Something like this:
This would add a text box that allows them to enter a quantity. You would want your developer to also add code to validate what is being entered to ensure that it's only an integer. Alternatively you could use a drop down menu if you want to restrict quantity options (1,2,5,10,20, etc).
I hope this helps! 🙂
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