Epiphyllum red tip
cacti originate from the moist and humid rainforest. Not from the dry desert, like most cacti.
This means that your cactus likes a bit more water than the average cactus. Make sure it gets enough water, especially during spring and summer. Mist it occasionally for a little added humidity.
Keep the soil moist and fertilize during the growing period. In winter let the top of the soil dry out before watering. It can handle a little neglect, but jungle cacti don’t like it to be bone dry for too long.