The question is what you do with the e-mail address. e.g., if the page would say: 1. "we provide this book for free, but collect your e-mail to follow up once

The question is what you do with the e-mail address. e.g., if the page would say: 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 ..., ..., ..."