Playlist with custom start video doesn’t work

Trying to embed a playlist that starts at the fourth video in the list, rather than the first.

Following all the instructions in the plugin (free) and the video (posted in a similar question a month or so ago) and still not getting results.

I go to the page with the playlist videos listed, go to the video I want, select the URL, put it into the box in the popup wizard, and it just gives me a shortcode for the playlist from the start, not starting at the video in question.

Thanks