I can't find my download files on Firefox Android

Hi everyone. I've downloaded some .mp3 files with Firefox on Android. The downloads are completed but when I open my Music app, I can't find those .mp3 files. I go to My Files (Samsung) -> Downloads (or Audio or Internal Storage -> Android -> Data -> com.org.firefox... etc) but i can't still find my files! I go to Tools -> Downloads, my files still there, i click on it but it just play, no "open destination folder" option. So how can i find my files? Please help me. Thank you very much!