When a user books a course, I generate an invoice with an API call to our online invoicing platform. As a result from that call I receive the URL for downloading the invoice as PDF which I save in Zoho Creator. 

The next operation is to send an email to the user with the generated invoice attached. Adding a link in the mail to download the invoice is not an option, since the link contains our API token for the invoicing plattform. 

Is there a way, that I can download the pdf file to a File Upload field in ZC? Or is there another way I could send the file as attachment through scripting? What I don't want to do is each time download the file manually after it has been generated and then manually update a File Upload field.

Thanks for any suggestions!

Michel