Drip Campaign Best Practices

I'd like to add a pop up on my website that invites visitors to download a how-to PDF, then, using the email address they enter I'll begin an email drip campaign. I see Squarespace has all the tools I need but I'm not sure the best practices I should use to do this effectively... or maybe I should separate this and use Mailchimp instead? 

Here's a bullet list of what I want to do:

- create a pop up that says, "hey there! sign up and download this helpful resource that'll solve your problems!" 
- once they add their email address a PDF is sent to them (it's the resource I mentioned in the popup)
- In the following weeks/months I'll send a weekly email with more details, offers, testimonials, etc..

also:
- Ideally this same email signup form can be used on my website too. That way I can have the offer in a pop up and in the body of some pages. 
- Can I export email lists that are created within Squarespace?

Assuming this is possible and reasonable within Squarespace, how do I best accomplish it? Do I use Mailing List or Newsletter? Should the free PDF be part of a Store and I just create links to it within my popup? Or is it best to do all of this through a third party like Mailchimp?

I guess I'm looking for best practices for creating a popup which trades a visitor's email address for a helpful PDF and a number of emails over the next few months. And should it be done entirely within Squarespace or using a third-party?