Once you fill out the form, you will receive a confirmation email with direct download links for the template. The downloads will be ZIP files that contain a Word Doc file and a HTML file. Though you will only need to work with the HTML or Word Doc, both formats are included.
If you copy and paste the HTML code into your ESP's editor, you should be able to easily swap out images, colors, and modify the text. Likewise, you can directly modify the HTML code in the text editor to swap out links, images, and hex colors.