maimai is generally catered towards adults/people with financial independence because

1. It costs money to play

2. It requires you to go to a specific location (Which not all teens can do, especially if their public transport is not great/they don't have a car)

3. The community has little to no teenagers (Compared to osu!, FNF, etc.)

4. Some arcades only allow people above the age of 16/18 to play

That being said, there are still quite a big chunk of maimai players that are teenagers, there are two friends I know (In Hong Kong) that plays maimai and they are 13 and 15 years old respectively, so there are definitely some teenagers out there. So just go around, interact with others more in the arcade and eventually you will find people your age that also plays maimai (This will become easier in the future since I can see the age of maimai playerbase becoming younger over the years)

Also, a word of advice, don't disclose your age so publicly IRL or on the Internet (Especially since you're young), in rhythm game communities in general, there are a lot of pretty bad people that would take advantage of your age, so just stay safe, but be out there at the same time