Problem embedding page content into template

I am building my second site with Ghost and I am developing my own theme. I want to take content from a page on the site and embed it into a template. This worked fine on the first site I made, but will not work on the new site I am making.

{{#get "posts" filter="page:true+slug:footer-nav" as |footer_menu|}}
    {{#footer_menu}}{{content}}{{/footer_menu}}
{{/get}}

This code works fine on one Ghost site but not the new one I am making. I have created a page on my new site with a slug “footer-nav” and it will not embed. It works on my first site though. I did notice that my first site is version 2.19.4 and my new site is on 2.21.0.

Is this a feature that has been depreciated?

In digging into the logs, I see this error:

"DisabledFeatureError","statusCode":409,"level":"normal","message": The {{#get}} helper requires your theme to have API access.","context":"\"Please enable the v2 API via your theme's package.json file.

Is my code simply going to fail in new versions of Ghost? Is there an alternate way to embed page content into a theme?

I accidentally got it working. I put {{#get "pages" instead of {{#get "posts"

{{#get "pages" filter="slug:footer-nav" as |footer_menu|}}
    {{#footer_menu}}{{content}}{{/footer_menu}}
{{/get}}