There is no way you can convert a media playlist file, such as .m3u to actual audio file, which of course includes .m4a (MPEG-4) files as well. At best, you can open the playlist in some text editor and check for the names of the songs and file paths that are listed in it.
Open M3U file Open M4A fileA music library management program - renamed to Helium (version 12) and replaced in 2016