Other HN members have pointed out previously, that it looks like a landing page where you need to leave your e-mail address. You don't. You can download the PDF from here directly.
Why do you have it as a PDF hidden behind a call-to-action reminiscent of a sign-up though? Turn it into a website, that'll make it a lot more accessible - assuming getting people to read it is the goal, of course.
Simple cost/result calculation. Creating a PDF + simple web page was something our designer can do easily. Developing a whole website around would have been much more expensive.
Other HN members have pointed out previously, that it looks like a landing page where you need to leave your e-mail address. You don't. You can download the PDF from here directly.