adding a quantity to an e-product

Site URL: http://www.surveyofmath.com

Looking for help writing a custom code for a client's ebook.  I have already talked to customer support and they could not provide a solution.  I have a client I designed a website for supplying teachers/schools with an e-book (text book) for students. The client needs a way for the schools to be able to pay/purchase multiples of the book.  I understand that because it is a digital PDF, the system doesn't see a need for allowing multiple quantities to be purchased since once you download the file onto a computer it can be shared, which is fine, but because they are providing it for multiple students, I need a way for them to "pay" per book each semester as they would do if purchasing a hard copy.  In short ( although actually long), I just need to write a custom code that allows multiples copies of the book to be paid for as it is when purchasing a physical copy of something in the cart.  Hope this makes sense, thank you for any and all help! 

27 minutes ago, Shutterup said:

The client needs a way for the schools to be able to pay/purchase multiples of the book.  I understand that because it is a digital PDF, the system doesn't see a need for allowing multiple quantities to be purchased since once you download the file onto a computer it can be shared, which is fine, but because they are providing it for multiple students, I need a way for them to "pay" per book

Some other platforms like SendOwl support this, but it isn't possible on Squarespace. 

A customer will be able to purchase multiples if you add the product as a 'Service' product, but the product will not be sent automatically. If the product is added as a 'Digital' product for automatic download, the customer can only purchase one. On Squarespace, it isn't possible to change this, with code or anything else.