“There are two ATMs in the train station and a currency exchange counter in the international section that has reasonable, if not outstanding, currency exchange rates. It’s wise to get your kuna before hitting town.” – from the web.
Take a walk (cca 15 minutes) from the Zagreb Central Station to the Hotel International Zagreb.
Some advices for the shortest route
The key step is to head left after you exit the train station. In about 50 meters there will be the IMPORTANNE CENTAR. It is an underpass you can go into. Once in it, turn left and head towards the bus station. When you exit the underpass, go straight and then turn right so you can reach MIRAMARSKA street.