Here is the full list of all 21 Bibi & Tina - there are New adventures with horses achievements.
Complete 10 main missions
Complete 20 main missions
Complete all main missions
Complete all side missions
Win a time trial
Win a steeplechase
Win a slalom race
Win a paddock race
Win five paddock races
Win all paddock races
Take all the photos
Clean up all locations
Unlock Stevan
Unlock Topsy
Unlock Miraculus
Unlock Nora
Unlock Pascal
Unlock Kyra
Unlock Cleopatra
Collect all the cups hidden in the world
Complete all the game's content