Yup, I just need to download from the playstation store and not through the game...
I already bought Meisou Mind for most of the idols!
Too bad for one 3,000 yen card is only enough to buy three songs for all idols and maybe an accessory... I ended up buying two 3,000 yen cards, so maybe I'll only end up buying Meisou Mind, Cosmos, Kosmos, and Mega Au Toki, plus a few outfits and accessories.
Wish there was a "buy for all idols" option for songs, maybe at a bit of a cheaper price than if you were to buy them all individually, like how subscriptions for things work. xD
Edit: Wait a minute... I'm able to download through the Playstation Store, but the content is out of date.