Dear Amit,
As I said, the FAST models of the CART wind turbines at NREL are not in the public domain, but are only available to specific collaborators. To request one of the CART models, you should contact Alan Wright or Paul Fleming of NREL. Alternatively, you can use of the other FAST models we do include in the FAST archive, such as the WindPACT 1.5-MW turbine (Test13.fst) or the NREL 5-MW baseline turbine (Test18.fst).
Best regards,