Is there Uber in Croatia? If not what is a good way from the airport to town?
I know there are taxis. There is also a shuttle bus. Tip: Airport websites always have this info--see https://www.zagreb-airport.hr/en/passengers/to-from-the-airport/35 for bus schedule
Take the shuttle bus to the bus stop in town. The bus stop links into the tram system. You can get tram tix at the tabback at the bus stop. 4K for a ticket (50c). Bus is similarly cheap - maybe 15K. Zagreb is not a big town.
To answer your question, yes, there is Uber in Croatia.