In your Gutenberg editor, find the HTML5 Audio Playlist – Extensive block and insert, just like others block.
Select the block, you will see the settings option in the right sidebar. You can see there are 2 tab for configure: Content and Settings.
At first let you know that you can add or remove audios for playlist from the editor.
Select the and audio item and you can upload audio file, poster change audio title and artist from content.
Switch to settings tab. From here you can change player theme and set width, height and poster height of the player.