This demo page has an ACF Custom Field group attached to it. All the output you see on the page below is from ACF Render shortcodes embedded into HTML in the page content editor. In practice you’d usually put the content in a custom page template or post template.
In these example the “post” and “template” options are not set in the acf-render shortcode. As a result the current post (this demo page) is used, and the default template is used. You can omit the “post” option when you know that $post is available in the loop, or template. If you put the acf-render shortcode somewhere else where $post is not available, then you should specify the post ID that has the ACF fields attached. When using a custom template, you would specify your template name in the “template” option.