Cannot insert shortcode on newsletter page

Hi there,

I'm trying to set up my newsletter to my blog page (stephaniecooke.ca/blog) and it says that the shortcode is not set up. Specifically it says, "The WordPress page "Blog" set as Newsletter's public page on the main settings does not contain the [newsletter] shortcode.
Edit the page and add the [newsletter] as the only page content."

But there is nowhere for me to put this. My "blog" page doesn't have a text box, it's just a category for my newsletter and blog posts. How do I get this resolved so I can activate my newsletter for my subscribers?

Thanks!