The best and cheapest way to go to Ayia Napa and Protaras from Larnaca Airport is by using Kapnos Airport Shuttle Only 8 Euros each direction!
Pick up points and prices: https://www.kapnosairportshuttle.com/faq?locale=en
TimeTable: Larnaca Airport → Ayia Napa
TimeTable: Ayia Napa → Larnaca Airport
For more info call: 00357 24008718 – Open 07.30 to 23.00 hrs.