Must one who has reached the age of fifteen make up missed fasts, and what are the consequences if one delays making them up until a later Ramadan according to the Maliki school of thought, and is a shower sufficient for performing ghusl from janabah according to the Maliki school of thought?

Whoever reaches fifteen lunar years has reached the age of responsibility (taklif) according to the majority of scholars. He must make up for the Ramadans he missed before the next Ramadan begins. If he neglects this and Ramadan enters, he must make up for it along with the minor expiation, which is feeding one poor person for each day. As for the well-known opinion among the Malikis, the age of puberty for them is eighteen years. Therefore, it is not obligatory for someone who has reached fifteen but not eighteen to make up or fast Ramadan, unless his puberty is confirmed by another sign.