There were some problems with syncing my phone with an on-board computer decided to get all the songs on USB like back in my day, but it seems that there're no more websites with free music. Though can I find any?
The simplest way to save money on music without breaking a law is to just buy a Youtube music premium subscription. The app allows you to save music on your phone, but you're going to need to transfer that music to your PC and only then on your USB drive. If you want to download actually for free and something like ramin djawadi the rains of castamere - extended version here