Error type: "Forbidden". Error message: "Requests from referer https://www.googleapis.com/youtube/v3/playlistItems?part=snippet,status&playlistId=PLKz6st_SK-xt9oPs9WiKCMqs8sCBqdHEZ&maxResults=4&key=AIzaSyAs6M43B7f5Et2Q7mjDGb8HilonktS_6Lg are blocked." Domain: "global". Reason: "forbidden".

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

Check in YouTube if the id PLKz6st_SK-xt9oPs9WiKCMqs8sCBqdHEZ belongs to a playlist. Check the FAQ of the plugin or send error messages to support.