Hey I know a little about this - you might've been hit by Instagram's anti-bot/anti-troll filter. Especially if it was a ban and not an account creation error. This could be for literally any reason (presence or absence of certain cookies, IP location and service provider, the name you used and how fast you filled out the sign-up, anything).
Just go through the account reinstatement process, which is actually in and of itself a form of checking that you're legit (since a real bot would just try again). There's not much you can do about it if it does turn out to be a troll detection flaw. They use algorithms that don't necessarily minimize false positives so that they can actually make a dent in the tide of bots and trolls.