18 is the legal age in Taiwan . So you may not be able to sign contracts to rent an apt, get a bank account or stuff like that . But lots of 17 year olds split from their southern taiwan homes to taipei. What they do is get a friend who is at least 18 to do all that stuff for them (in their name).
You cant get a drivers license either, course that doesnt stop people from riding a scooter. After all see all those people who RIDE their scooters to the license testing site, fail, and then ride them home again for a try another day.
How long do you intend to stay in Taiwan? What do you plan to do here? Have you graduated from high school? Do you have friends/relatives/acquaintances here?
You might get better advice if you give us more details like these.