you get digimon the same way you do in digimon world ds you keep finding a digimon until you get 100 percent scan data and than go to your digilab system and choose digiconvert and select the digimon...
after you get digimon at the start you go through the tutorial and find the portal to go to chip forest etc and battle the same kind of digimon (you can just flee) enough (until 100% scan data) and...