To tame an Armadoggo drop the food that you want to use from your inventory to the floor near the Armadoggo. It will start to smell around it until it goes towards the dropped food, then the Armadoggo will start to eat it and after it's done the player needs to pet it quickly before it buries itself into the ground and appears somewhere else near. Repeat this process until the taming completes.

Passive: You need to tame it while the Armadoggo is awake.