What are the tank dimensions (length x width x height)?
Has the tank been cycled?
If not I would suggest doing a fishless cycle or using filter media from an established tank. Rift Lake cichlids live in hard alkaline water and any ammonia in the water will quickly harm the fish. An established biological filter is essential to prevent this happening in Rift Lake tanks.
If the tank is 30 inches long you could have about 6-8 fish. If it's only 24 inches long then 1 male and 3 or 4 females.
The stocking levels are for adults and a batch of young fish up to about half grown. At which time the young will need to be removed or possibly get attacked by the adults when they breed again.