I’m not of the Catholic faith. :-) And Cardinals are not Apostles, as far as I understand the Catholic faith. If I’ve misspoke on that point, I’m happy to be corrected by someone of that faith.
Cardinals are the “Princes of the Church” picked by the Pope usually Archbishops or from the Curia assisting the Pope in governing the Church. The organization and hierarchy of the college of cardinals consist of Bishops/Priest/Deacons for ceremonial purposes.