Apple snails are not a good addition to a cichlid tank. Cichlids will aggressively attack the snails and may kill them.
Apples do not eat algae. They need to be fed a calcium-rich diet of fresh veggies just as you would feed any other invert. Many species of apple snails are illegal to ship across state lines, but it is not illegal to simply own an apple snail in any state. Pomacea bridgesii - mystery snails - are legal to ship with a permit and can be found in most states.
All apple snails are heavy waste-producers and will add to your bioload as much as another fish would. They're not a good choice for algae cleanup. It's better to determine the cause of your algae rather than look for a snail or fish to clean it up. Too much light, too high nitrites or nitrates, excess phosphorous are all potential causes.