Would adding a second checkbox ("I'm not a resident of the EU") be a way for a site owner to still provide this to exchange to non-EU residents?
1. "we provide this book for free, but collect your e-mail to follow up once in about 1 month time with a relevant offer." ==> this might even work from a "legitimate interest" view, but thats currently not well defined
OR
2. "click here to provide consent for us collecting your email and using it for ..., ..., ..."
Below the form the intent is clear, but you should also be allowed to only get the ebook without having any further email from me.
edit: You may of course not like my comment, but it is factually correct: GDPR really doesn't forbid combining the newsletter entry with a bait like a free ebook, as long as you don't phrase the newsletter membership as "free" and use double opt-in.
This seems to indicate an "email to download a whitepaper" scenario is in violation. Now... "downloading" vs "delivered to your inbox" might be a distinction to draw. Whether or not it's actually a violation, info pages like the one above seem to make it appear to be a violation.