Well once you launch Subnatica and get into your world, you can press x,a,rb,lb at the same time which should open a screen called dev concel, once this opence you just enter a pc cheat code and it should then work, P.S. all cheats get disabled when you leave the game, so you will have to renter them every time you load the world.

Code	Effect
Allblueprints	unlocks all blue prints
Madloot	Free useful items
Oxygen	Infinite oxygen
Radiation	no radiation
Spawn seamoth 1	Spawn seamoth
biome (name)	teleport to biomes
day	set to day
fastbuild	faster building
item (name of item) (amount)	spawn item
night	set to night
nocost	can make anything without any materials
nodamage	Take no damage
sub Cyclops	spawn Cyclops
warpme	teleport to safety