Croatia was late to the game, only getting its code when Yugoslavia broke up. By then .cr was already taken (Costa Rica). So were .ca, .co, and .ci - Canada, Colombia, Cote d'Ivoire. .ct was available though.
not necessarily, local name is Hrvatska so it's questionable if they would have assigned `.cr` had it been available. Most users of `.hr` sites are locals so it makes sense to them but have seen confusion on websites that target foreigners.