Mailchimp pdf download email/automation

I have a Wordpress site with a Mailchimp newsletter already connected. (newsletter is sent monthly).
I use Poptin to gather signups which go via Mailchimp. After signing up people receive a welcome email an hour later.
I have one page on my website that receives apprx 50 visits per day. I have a downloadabe pdf for visitors to that page. So I need to create a separate sign up form enticing people to enter their email to receive the pdf. They'll then receive the pdf link email but with a note to say that they've also been signed up to my monthly newsletter (with option to unsubscribe, of course).
I need help setting this seperate automation up.