You can not use our builders for those pages, as it is set as the posts page and all the information and layout of the page is retrieved from the PHP file responsible for the layout.
You will need code customization to add any kind of information or shortcode there. Customization of the theme is outside of our support scope and we will not be able to implement the feature for you, but we can give you the correct direction to do it yourself.
Please install the Child Theme and copy the file below:
You may need to add proper folders in your child theme to copy the file.