Surely you no longer offer your valuable whitepaper for download, but ask for the visitor's e-mail address beforehand. This can be easily done with a marketing automation tool. The document is then conveniently sent by e-mail and you receive important information about your visitors or even convert them into a lead. As you are used to from countless forms on the Internet, there is also the mandatory data protection checkbox here, which must be checked before submitting.
At the same time, you should also ask to register for the company newsletter, as this is the ideal time for this. When the visitor is ready to swap their email in exchange for a helpful white paper, the step to receiving additional documents is not far away.
The HTML templates in LUX can be extended with any additional fields - here with a checkbox with the name "newsletter" and the value "1":