I suggest adding an endpoint in documents to create a shareable link through a POST request with an email address on the body.
This actually can do it manually in Sales -> Documents -> Create Link, but you can't create shareable links by email dynamically. That would be amazing to complement with Forms API.
The complete idea is adding contacts through a Hubspot form with a custom HTML in a website that sends a request to the backend, then to Hubspot Forms endpoint, then to a new "Shareable Document Link" (idea) endpoint with the email address in the body, and send an email with the e-book link through our mailer provider.
With that, we can collect contact data and send an email with a link or simply redirect to the document link.
