You can try our Oxilayer PDF Invoice generator app: https://apps.shopify.com/pdf-printer
It should fit your needs. There is the option to include invoice or receipt PDF download link into Shopify “Invoice”, “Order confirmation” or other email. Also PDF templates are fully customisable, so you will be able to insert any necessary information for your invoice.
Here is how it can be configured: https://www.youtube.com/watch?v=zZmc4LsVTnI