I must be dumb

Beven,

Did you paste the URL on its own line?
https://s.w.org/plugins/embedplus-for-wordpress/screenshot-1.jpg?r=908068

It’s unclear what’s happening without seeing what you actually put in your editor. If you’re really stuck, we suggest that you use the wizard provided by the plugin.
https://s.w.org/plugins/embedplus-for-wordpress/screenshot-2.jpg?r=908068
It will give you shortcode to paste.

Good luck,
-EmbedPlus Team

closing