note: You don't state this in your question but based on your example it appears that you are trying to play an audio file after a 4 second delay.
The (live:) macro is a type of loop, it executes the contents of it's associated hook every X milliseconds until either:
a. A Passage Transition occurs.
b. A (stop:) macro is used to end the loop.
To use the (live:) macro as a form of delay you need to call the (stop:) macro so that the contents of associated hook is only executed a single time.
<audio src="https://www.dropbox.com/s/tzhqrnqheccr7cm/Metal%20Hit%20Sound%20Effects%20All%20Sounds.mp3?dl=1" autoplay>
a. The above code is untested because I don't have access to your audio file.
b. Folder & File names are case sensitive in most Operating Systems (excluding Windows), because of this web-developers generally only use single case letters (lower-case) when naming them. Space characters can also cause issues when used in folder & file names, because of this web-developers generally replace them with either a standard dash / minus sign character (-) or a standard underscore character (_)
c. Many modern web-browsers (especially those used on mobile devices) don't allow the autoplaying of media files until after the end-user has interated with the web-page. (eg. clicked on a link, etc...) Because of this autoplaying a media file within the first Passage of a story may not work.