Conveyance deed of housing society formed within Integrated/ special t

Life republic township formed under integrated township act of maharashtra. There are various sectors i.e. group of buildings. In agreement for sale, it was noted that condominium will be formed after building completion and flat owners will have no right to additional FSI that may be alloted to township in future. But due to RERA builder has formed co-operative housing society. Now, flat owners want Conveyance deed in the name of housing society. Builder says he will only do conveyance deed for Floor Zero plus podium. Minus one(actual land) and open area and club house will still remain under builder. As per my understanding conveyance deed should transfer land within sector to housing society. But what builder is saying contradicts the concept of conveyance deed. finally to who should own the land?