We didn't use them for your route but took Costa Rica Driver and Adventure from the Papagayo Peninsula to Arenal and did a "tour en route," (rafting), then used them to come back from Arenal to the Liberia airport. They were great, the owner was very communicative over WhatsApp (he actually drove us back to the airport), and the stop was well run and fun. Definitely recommend!

https://www.drivercostarica.com/en/

We used this and found it very professional. We did 3 transfers and they all went well Communicated on WhatsApp
https://www.playagrandeshuttleandtours.com/

We would like to be picked up at the airport in San Jose and driven to Tortuguero (or rather, driven to La Pavona to catch the boat to Tortuguero). Can anyone recommend a private transfer company in Costa Rica that they used? Thank you.