My friend got into the music business lately and I'm thinking of buying likes for his latest music.
Why are you thinking about buying likes?
Some people have been saying that it's a pay to win scenario
If your friend doesn't earn their likes then people will think they are a fraud. He should find out why he isn't getting likes organically.
Well, then I would need to get more likes to show people that he is getting popular
You could show off his music to others? You could try going around and trying to find ways to get him more likes? Just manipulating the reviews will make people upset at the dishonesty.