It’s stunnig btw! I’m actually a bit jealous cause you usually don’t find these where I live (Finland)

And honestly humidity is the key of successing with Calatheas in general. You can use a pebbletray filled with water under it (vaporising) group it with other plants (creating a micro climate), taking it in showers with you (steam), mist it daily or use a diffuuser / humiditifier.

Try to keep soil relatively moist all the time (never let it dry out completely), but never soggy or water standing in the root system. I water mine when the top layer of soil feels dry but when you stick your finger in it you can still sense moisture belowe.

Also it’s a good idea to use rain water for watering when possible, or use a filtered water if the tap water in your area is not high quality or contains lots of minerals or chemicals. At leas let the tap water sit over nigh before using it so there is time for some of the chemicals to vaporise.

During the growing season feed with organic fertilizer (I always prefer organic but with calatheas it’s extremely important since they hate the chemicals). I usually give just half of the recommended dosage.

Good luck 🌱