For as little as $28 (€23) you can travel by bus to Rovinj from Zagreb with FlixBus. Omio will show you the best deals, schedules and tickets available for this journey.
FlixBus is one of the most popular low-cost bus companies in Europe. Founded in Germany, FlixBus has expanded its services throughout Europe and even to the United States, giving travelers in both continents the option to take a long-distance bus at an affordable price. FlixBus also operates overnight buses on select routes throughout Europe. FlixBus offers only the Standard ticket for all its routes, which allows you to bring one carry-on bag and one checked bag per person. Additional fees apply for bringing extra luggage and making specific seat reservations, such as if you want to book an Extra Seat, Table Seat or the Panorama Seat. Standard amenities onboard include free Wi-Fi, power outlets to charge your phone, tablet or laptop during long bus journeys, extra legroom, luggage space and toilets.
FlixBus from Zagreb to Rovinj bus information:
These are FlixBus' ticket policies for COVID-19 for the bus to Rovinj from Zagreb:
Here are some other resources that might have the information you need