You either download the CGI script and host it yourself or you pay the formmail.com people to host it. In the olde days there were free ones where you specified the destination in the form, but spam put paid to that.
It's free, unless you exceed 1000 submissions/month:
> How much does it cost?
> Formspree is free for 1000 submissions per email each month. If you need more, please reach out.