Complete the main quest chain up to and including Whispers in the Walls
Unlock the Dante acquisition content from the Sanctum Anatomica on Deimos
Farm the required Dante blueprint and component blueprints from the relevant mission/reward sources tied to his release content
Gather the required crafting materials from missions, enemies, and open-world/quest content
Craft the components in your Foundry
Craft Dante in your Foundry after all components are complete
Alternatively, buy Dante from the Market with Platinum to unlock him immediately