From Zagreb to Tisno, there is a travel distance of about 330 km, following the Croatian highway. Most buses follow this route, but there is also buses following the toll free route along the country road.
There is a handful of direct buses between Zagreb and Tisno, during the summer season, as apposed to most of the buses from Zadar and Sibenik, the buses from Zagreb actually goes to the town Tisno, which means you can get out by the festival area, if you are going to one of the many festivals in Tisno.
Driving time for the bus from Zagreb to Tisno is about 5-6 hours.
Here you can see current timetable: