Can’t get Yottie light to workon wordpress

Hello,
I have downloaded & activated the Elflight Yottie light on wordpress. I have entered my Youtube channel url into the installation box, the url of which is https://www.youtube.com/channel/UCpg-pYIg34MZPal3Te4U0KQ.

I have not entered the Youtube API Key, because I do not know how to do this, and the link to the tutorial: How to get YouTube API key, does not work either.

I have copied the shortcode into a widget shortcode box on my wordpress page editor, but no video channel appears on the page.

1. Do I need the API key in order to get my YT channel to appear or if not, why is the bx there asking for an API key?

2. What am I doing wrong or what is the problem please?

The page I need help with: [log in to see the link]