This trophy is cumulative, as it tallies your highest scores across all the songs you play. There are thirty songs to play, so a good start is to unlock and play all the songs. This, unfortunately, does require higher difficulties, as Beginner just doesn't offer enough points to build up to this total. Even on Intermediate, you'll be cutting it really close unless you can get lucky with multiplier powerups.
If you're unsure how much more you need, you can check the total score leader-board on the main menu. This can come naturally if you can combo consistently on Expert or Super, but if you're like me and a bit less gifted at this one, I ended up unlocking it after playing all but five of the songs on Intermediate while keeping steady combos throughout. The rest were done on Advanced.