Whenever you’re prompted to make your own song throughout the series, yes. In the current release, MC hasn’t quite reached that point. You won’t ever really have a set genre, you’ll just choose what genre you want each specific song or album to be in for the most part. Though this is more-so for the later episodes.
I suspect that most readers will tire of writing their own songs sooner than you’d expect, however, so often in the prologue MC just covers songs. Whilst writing your own song is appealing at the beginning, and always to me as I’m a musician irl lol, many would simply hate the idea of having to generate their own lyrics time and time again and then generating an internal melody that they think actually sounds good and or believable for the scene. So it’s a bit of a mix. You’ll definitely have your own options to choose genres, but most of the time I’ll likely write the lyrics of a song myself, primarily chorus, and have readers input only one or two lines as opposed to seriously asking anyone to input a full 20-40 lines per song. Also, particularly in episode 3, (which is still a ways off) MC will often simply collab with different artists who come with their own genres and simply ask MC to feature. MC will be known as a popstar, but never limited to the pop-genre. Opportunities will come to learn different instruments (one such is available in the current release), and genres from different people such as how to rap among other things.
In this same sense, you may notice how you aren’t prompted at any point to choose a vocal classification. This isn’t an oversight, rather that this simply won’t be an option until episode 1 when MC is an adult. Primarily due to how male voices change in late puberty above all else. It would be beyond foolish to describe MC as a deep bass at 14 years old after all, a man’s voice typically only ‘settles’ around 20, so it was best to add that touch of realism to it. MC’s greatest skill is versatility, so I don’t particularly see them being universally defined by any one genre, rather someone who can and will switch between genres depending on the players whims. (Or maybe they always stay in one when possible, if the player so wishes!)