Error type: “Forbidden”. Error message: “The request is not properly authorized to retrieve the specified playlist.” Domain: “youtube.playlistItem”. Reason: “playlistItemsNotAccessible”. Location type: “parameter”. Location: “playlistId”.

Did you added your own Google API key? Look at the help.

Check in YouTube if the id PLLhQziLm_tMlRAvQEtN5kU2w40n0X1P53 belongs to a playlist. Check the FAQ of the plugin or send error messages to support.