Now navigate to the WordPress Admin Dashboard →Plugins→Add New.
Search Classic Editor in the search bar.
Once done, install and activate the Classic Editor plugin.
Once done, if the Admin is using the Classic Editor, after setting up the Post Snippet, a Post Snippet Insert button will be enabled in the page and post editor.
This allows you to insert the snippets on the page.
Click on the Post Snippets button that appears on the editor toolbar.