The good news is our Lead Generating Landing Page can do exactly this! You can create multiple versions of these forms with unique URLs. Not only can they be used to capture the contact information of new sign-ups, but you can also include a downloadable file on your Thank-You page.
I apologize if the feature I shared was not the answer you were looking for! If you are looking for an option that can be directly in your website, have you tried one of our inline sign-up forms? These forms can be embedded into you site. You can also connect an automated email to the contact list you have selected for this form. An automated email series can include your PDF/freebie in it and automatically send to your new sign-ups.