Can the Authorities FBI CIA or NSA send you warnings through your iPad?

Answer 1

Can they send you warnings? Yes, if they really wanted to, but they have never been known to do so. If they want to contact you they do it through more obvious means such as showing up at your house, apartment, dorm, school, or place of business and inviting you (firmly) to come speak with them. There are some organizations such as US-CERT that can send you alerts/warnings if you have signed up to receive them, but they don't send them out unsolicited.

That question sounds very much like one someone might ask when they have visited a questionable web site and been hit with a "scareware" warning. Scareware is a type of social engineering - often combined with another kind of malware - intended to induce fear, anxiety, shock, or other wise induce the victim to feel threatened. It often is intended to trick a victim into installing some malware on their computer (under the guise of protection) or purchasing some worthless software or getting them to send money to the perpetrator as a "fine" (effectively blackmail) .