Not sending anything

Hi there,
I want people who send the form recieve in a pdf copy so I think this is a great plugin… but I don’t know how it works.
My steps:
– I’ve just installed it, and activated
– I’ve added the id of the form I want to send by pdf on the page “conf7_mail_pdf_ext”
– Go to the page where I have the form and send the form
The form is working but no file is attached…
What else I have to do?

https://wordpress.org/plugins/contact-form-pdf-extension/