At first go to your Gutenberg Editor and insert HTML5 Audio Player block like before.
Select the block, you will see the settings option in the right sidebar. You can see there are 3 tab for the settings: Settings, Controls and Style.
From the settings, at first you can change the skin of the audio player, there are 3 skin available: Default, Fusion and Stamp.
Also, you can enable/disable Repeat, Autoplay, Muted and set Seek Time.
You can upload audio file or change the audio URL in default skin.
For the fusion skin you can add audio title, upload audio file and poster.
In stamp skin, you can add audio title and upload audio file.
In controls you can show/hide the as Restart, Rewind, Play, Fast Forwards, Progress, Duration, Current Time, Mute, Volume, Setting, Download.
Note: controls are only for the default skin.
You can change different style for different skin.
Style for default skin
For the default skin you can change primary color, hover color, background color, width and border radius.
Style for fusion skin
For the fusion skin you can change width and border radius.
Style for stamp skin
For the stamp skin you can change text color, width and border radius.