Taxi
The public transportation from Samana to Cabarete is very basic. From what I know, there are medium sized buses that make specific stops and guagua vans
that make lots of stops and are often crowded and uncomfortable. From the airport in Samana, your best bet is a taxi. I don't know the price, but I'm guessing at least $100 US dollars. As you probably know the Puerto Plata airport is much more convenient to Cabarete. Another option is to rent a car, but the roads are in terrible condition with many deep potholes. You don't want to drive at night; trying to navigate in the dark unknown is suicidal. The drivers in the DR are another breed, many motoconchos with no lights, other obstacles abound...
Maybe someone can recommend a driver with whom you can make arrangements for your pick-up at the airport? Or think about renting a car if you're arriving at least 2 hours before dark.