Magnagarurumon is a Digimon from the "Digimon Frontier" series, not "Digimon World Dawn."
In "Digimon World Dawn," the only way to get a Garurumon line Digimon is to evolve a Gabumon:
* Gabumon -> Garurumon: Evolves at level 25 with a high Training Point (TP) score.
* Garurumon -> Weregarurumon: Evolves at level 40 with a high TP score.
It's important to note that while Magnagarurumon doesn't exist in "Digimon World Dawn," other games like "Digimon World Re:Digitize" do feature it.