After ww1 and the depression that also struck europe, germany was completely broke. Where did all the money come from that was fed into the economy and infrastructure to feed the new war machine? Basically, who was Hitlers benefactor?
At first the money mostly came from Germany's Exchange reserves and other "hard currency" from before he took power. He also borrowed extensively from foreign sources.
By cheating: the Nazi government encouraged high savings rate from its workers, therefore it can simply pay the workers=>the workers put money in bank=>Government uses savings as capital for further expansion.
Later on, he looted countries he took, Germany was in a constant state of economic crisis in the late 30s precisely because he didn't have money. But annexation of Austria, Sudetenland, Poland etc allowed to loot those country for resources to fund the War machine for additional conquest for more loot and so on.