Crystal shrimp need a much lower pH and softer water than cherry shrimp do. So the RO water is good, but usually needs to be remineralized to some extent, as pure RO will result in pH swings that can kill shrimp. Test now to know what it should be.
Many shrimp keepers get a TDS meter, which measures total dissolved solids in water. It can help with getting the minerals right, though they can cost a bit.
There are products, if not at Petsmart, you can order online, to remineralize with and mineral stones for shrimp can be bought, which help too. They also tend to do best with food made for them, rather than fish food. Also available online. Mosura is one good brand name. There are others.
Test water regularly and make sure the parameters remain stable. Changes are usually not needed as often as with fish, but may be needed once in awhile. Testing often is the only way to be sure the water is ok for them, unless you wait 'til they start dying.
Feed very, very sparingly, two or three times a week. They are scavengers, so overfeeding just ruins the water. A feeding dish is helpful to keep food from scattering. A clean clay pot saucer works well.
Do more research.. there is tons of info to be found. Good luck