Install a "User-Agent Switcher" extension in Chrome or Firefox. Change your User-Agent string to emulate a player like VLC or an Android device, then attempt the download again.
Before downloading, you must understand why the URL is broken. Here are the top 7 reasons: fixed download m3u file from url
Downloading a fixed M3U file from a URL depends on whether you want to save the itself or the actual video content it references. 1. Saving the M3U Playlist File Install a "User-Agent Switcher" extension in Chrome or
Even experienced developers encounter recurring issues when downloading M3U files from URLs: fixed download m3u file from url