Use Modzilla FireFox browser (no Safari, no Internet Explorer, no Google Chrome) to open khonglottaimusic.com.
Go the post of the song that you want to download.
Right click on the music player.
Select View Page Info in the dropdown menu.
In the Page info, select Media option on top.
Highlight the Audio file of the song.
Click Save As to save the mp3 file to your own folder