CRM or other solution for this use case (collect mail addresses, provide documents)

Hi!

I want to give my customers easy access to a collection of pre-prepared PDFs, in exchange for their e-mail address. These documents should then be automagically mailed to them and I keep their address.

Customer has need -> follows link -> chooses documents from a list -> enters mail address -> documents get sent, I keep mail address.

*But* does it have to be a CRM for this? I keep thinking I could do this in JotForm… but don't see how. The files are currently hosted on Dropbox (my own website not yet finished).

Any ideas for automating this? Yes, I'm sure HubSpot have an option, I'm not sure I really want to go down that path.