static page with buton that opens collect email form

It looks like you are creating an HTML form that allows you to interact with the user. This form would collect an email address and upon successul retrieval it would allow a file downlowd.

For forms, your best bet is to install a forms plugin. A very good form plugin that is easy to use is Contact Form 7.

What you have to do is create a page via WP-Admin area, then create a Contat Form 7 add-on, and embed it in your page.