How to Use the Shortcode or Block with Feed to Post
Feed to Post works differently than the original plugin since it can convert feed items into WordPress Posts (or any other custom post type). However, you are still able to display the imported posts using our [wp-rss-aggregator] shortcode or the block anywhere on your site.
The only difference here is that, as of right now, imported posts displayed using the shortcode (or the block as of Core version 4.13) will link directly to the original source, not to the Posts on your site.
Alternative: Import Feed Items OR Posts
You may import certain sources' items as Posts and others as Feed Items. This allows you to create different displays. For example, the Crypto Headlines website uses feed items and the shortcode display on its homepage, while it imports videos as Posts and displays them separately here.
To import as Feed Items when using Feed to Post, within the feed source settings, set the Post Type to "Feed Item".
This allows you to display the imported items anywhere on your site using the shortcode or the block.