You must have a record go Gold, Platinum, and Multiplatinum respectively. Throughout Build a Label, your artists will release songs which you can then invest in, deciding how much money to spend on releasing it.
You can get this on the very first song you are able to invest in, which you can after helping Luda out. Focus on putting a majority of the money you have into Airplay, with a good amount into Marketing, followed by PR Appearances, and Cost of Goods. After you've done a few fights, Luda's song should go gold, with the achievement following.
You must sell 500k units in order for a song to go Gold.