During their Blitzkrieg in summer and fall of 1941 and the subsequent three-year war of attrition, German Wehrmacht and Waffen SS physically eliminated (exterminated) not only the 8-million invasion army, but 10-12 million more Soviet combatants.
Destroyed 100,000 Soviet tanks and self-propelled guns, over 200,000 of towed artillery pieces and mortars, over 100,000 aircraft, almost 40,000 armored car and half-track vehicles, 15 million of rifles, machine- and submachine guns, over 1,000 Soviet Navy ships – and demolished at least half of Soviet military industry.
Which delivered a lethal blow to Stalin’s dream of invading, conquering and destroying the Western civilization (by transforming it into a colossal totalitarian Bolshevist state – the global Union of Soviet Socialist Republics).
In the war of attrition, Nazi Germany survived and fought long enough for the Allies (the USA ad Great Britain) to develop both a nuclear bomb and the enormous fleet of strategic bombers (not to mention very powerful tactical aircraft, armored and motorized forces).
Which made any Soviet attempt to invade the Western civilization a guaranteed suicide. Hence, the Nazis achieved their most fundamental objective (and fulfilled their Divine Mission) – eliminated the existential Soviet threat to the Western civilization.
Stalin had to be content with conquering just a few East European nations – Poland, Bulgaria, Romania, Hungary, Czechoslovakia, Albania and Yugoslavia (the latter two very soon liberated themselves from the Soviet rule – but not from Communist totalitarian regimes).
He even was forced to leave lucrative nations of Austria, Norway and especially the oil-rich Iran. And had to conquer Asian nations instead – China, North Korea, Vietnam, Laos and Cambodia (although the latter three became Communist years after the death of Stalin).