Otvoreni Radio is a really cool modern radio station with up-beat content to listen to whilst relaxing, driving, working.
You can also download their mobile App for mobile devices!
Narodni Radio is another relaxed, very good popular radio station I like. You can also download their mobile App for mobile devices!
HRT radio stations are right for you, if you are in for the more serious stuff.
Just download from the App Store HRT Hrvatski Radio App! Plenty of talk, news, shows are on HRT radio stations Prvi Program, Drugi Program, Treci Program. In case you want to go local you have separate stations for Dubrovnik, Knin, Osijek, Pula, Rijeka, Sljeme, Split, Zadar.
There are plenty of other stations, but these ones I like personally most and these ones have the highest quality of content, if you would like to learn by listening and get involved in the latest actualities of Croatia.