Can I obtain information about someone’s Instagram account?
US federal law doesn't allow private parties to obtain account content (example: comments, photos and so on) from providers like Instagram.
Instagram may provide reasonably available basic subscriber information (not content), if any, only where the requested information is indispensable to a case and not within a party’s possession upon personal service of a valid subpoena or court order and after notice to affected account holders.
Your subpoena or Court order must be directed to the entity mentioned in the terms of service that are applicable to your use of the Instagram service (i.e. Facebook Ireland or Facebook, Inc., depending on where you are domiciled domiciled meaning if serving the subpoena on Facebook, Inc., the subpoena must be a valid federal, California or California domesticated subpoena, addressed to and served on Facebook, Inc. If serving Facebook Ireland Limited, the subpoena or court order must be addressed to and served on Facebook Ireland Limited.”)
Those seeking non-content information must specifically identify the account at issue by providing the Instagram username, profile URL and relevant date. We can't identify accounts without this information. Usernames and/or profile URLs may be found in the uniform resource locator available in a browser displaying the account in question. For example, in the URL https://help.instagram.com/abc, “abc” is the username.