How did the great depression and the german-soviet nonaggression pact lead to wwii?

The Depression was a global phenomenon, and Germany suffered extreme rates of joblessness and inflation during those years.  The very bad state of affairs in Germany allowed a radical group like the Nazis and a charismatic strongman like Hitler to come to power by making grand promises to the German people.  That was one factor leading to World War II.

Securing a non-aggression pact with the Soviet Union allowed Hitler's Germany space to expand its territory without feeling a threat from the Soviets in the east.  The non-aggression pact was signed on August 23, 1939, and shortly thereafter (Sep. 1, 1939), German armies invaded Poland and World War II was underway.   (Hitler later would break the pact and invade the USSR also, in 1941.)