This is an easy cactus to grow. Use a good draining Cactus and Succulent soil and allow it to dry our between waterings.
My experience with this cactus is that it can sunburn with too much direct hot intense sun. Therefore I like mine to receive some afternoon shade. I also have had one of these as an indoor plant for a few years now. I keep it rotated to avoid bending towards the light and I try and take it outside once every week or two to let it get fresh moving air and more light.
I have experienced that this cactus can be more prone to fungus issues. I like to give it a preemptive spray of Bayer 3-in-1 every so often.
My larger inside Fairy Castle is probably 2.5ft tall and a 1ft wide.
You will receive one cutting that may or may not be rooted.