aleant

The best (easiest) way is taxi. But, if you take a car located at the airport, it should be in the range 200-300 HRK (27-40€). I don't know exact price because I never use them, they are too expensive (they charge way more than companies from the city of Zagreb when they take you to the airport). Other option is Uber, should be around 100HRK (~15€). Croatia had changed regulation regarding taxis this year, so currently I don't know what is the status of Zagreb companies (Eko taksi, Cammeo, Radio Taxi Zagreb) to pick-up passengers from the terminal. (taxify also offers service in Zagreb, but did not use them yet, so can't tell anything about them)

Another option is to take a bus, Croatia Airlines buses are parked when you exit the terminal building, and they are going to the main bus station. Price is 30HRK (~4€) per person. The main bus station is 700 meters from the hotel, and I recommend you to walk the distance. You can take a tram (numbers 2/4/6, northbound direction from the tram station at main bus station), but since there is no tram station in front of your hotel, you will end up walking, but this time half of the distance (+ time you spend waiting for tram and buying ticket). Tram tickets are 15 HRK (~2€) in the vehicle, or 4 HRK (~0.6€) in kiosks around city (ask for half-hour ticket).

I usually use Uber or Croatia Airlines bus.

Not recommended (but cheapest) option is to go by public transportation (ZET company - running buses and trams in Zagreb). Bus 290 stops at the road in front of the terminal building.Their frequencies are very low (1 bus every 35 min), and it would take you transfer at Heinzelova street bus stop, where you should take tram number 2 going westbound (direction Črnomerec) and you should exit at Branimirova street (just after you pass the main bus station). Overall price for that would be 10 HRK (~1,5€) per person if you buy your ticket at the Tisak store in the airport building. This time ask for 90-minute ticket. My estimate that this trip would take you an hour...