Error type: "Forbidden". Error message: "The referrer https://www.googleapis.com/youtube/v3/playlistItems?part=snippet,status&playlistId=PLiwjE2lUypAkiBts59UktXVGiReumT-uh&maxResults=50&key=AIzaSyD70gJalQTZAMOKdC2n1CWinfWhX02SByk does not match the referrer restrictions configured on your API key. Please use the API Console to update your key restrictions." Domain: "usageLimits". Reason: "ipRefererBlocked".

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

Check in YouTube if the id PLiwjE2lUypAkiBts59UktXVGiReumT-uh belongs to a playlist. Check the FAQ of the plugin or send error messages to support.