Corrupted Dirt can be found on the Corruption layer deep underground on every Creativerse-gameworld, shaping the ceiling, the bottom and also walls in between together with Corrupted Stone and strands of Corrupted Wood (that has several patches of Corrupted Leaves growing from it hanging down from the ceiling and growing up from the Corrupted Water that covers most of the ground of the Corruption layer).
Nowadays you can also use Super Excavators that will remove an area of 7x7x7 corrupted blocks of any kind and save half of them in Loot Bags (that are prone to gravity and will drop to the lowest point or will sometimes be displaced sideways a little as long as there's free space). Any Lumite Nodes will be left untouched, and the Lumite Ore can be extracted with any type of Extractors.
If you do not plan to collect Corrupted Dirt but just want to dig through it, you can also use Super TNT that will blow a large hole into corrupted blocks of all types, and can even make some Corrupted Water evaporate along with it, if there is any in its range.
Alternatively you can also "purify" Corrupted Dirt by placing a Healing Beacon close enough or by throwing Purification Bombs and turn Corrupted Dirt into simple plain Dirt blocks by that. These can be pulled without even needing any Power Cell or can be destroyed with simple TNTs. Usually it will be hard to purify 7x7x7 blocks (and/or Corrupted Water) so that this amount of blocks can be removed with a basic Excavator.
In earlier versions of Creativerse, Corrupted Water and some solid corrupted blocks were able to corrupt simple Dirt to become Corrupted Dirt just as well by touching. This also reverted purified Dirt back into Corrupted Dirt in the Corruption layer. This is not longer the case. Corrupted Dirt was also able to corrupt blocks of Wood of any kind before R45, but isn't anymore.
On blocks of Corrupted Dirt all kinds of (aggressive) corrupted creatures and also occasionally Diamond Treasure Chests can spawn in darkness (where neither sunlight nor artificial player-made luminaires illuminate the scenery), no matter if day or night.
This also holds true for artifical biomes or "arenas" made by players wherever they like, as long as a large enough amount of Corrupted Dirt blocks are put together (usually large platforms of only 1 block "height" will already do fine for the purpose of "spawning" Corrupted Creatures and Treasure Chests).