German bombers were only two engines, lacking the range and load carrying capacity of Allied bombers. Germany's famous panzers had relatively narrow tracks which were unable to cope with Russian mud and snow. And the Wehrmacht relied on horse drawn wagons for most of their logistics. 80% of German infantry traveled on foot because the Wehrmacht lacked mechanized transport.
The He 177 had 4 enginges, if in an unusual arrangement. Over 1000 of the planes built. The Ju 290 had a more conventional 4 engine arrangement, but it had very low production numbers and was used primarily for reconisance and long range patrols rather than as a bomber. The Fw 200 could also be used as a bomber.
Part of the Germans problems was Hitler himself.
Hitler was adamant that the K98K Mauser bolt action with it’s 5 round stripper clip was the ultimate rifle for the Wermacht even though the 10 round Garand semiautomatic allowed for more time aiming and firing.
If the 1898 Mauser had been good enough for corporal Hitler then it’s descendants were good enough for his army.
Hitler fought the production of the StG44 until reports from the Russian front begging for more of the rifles were made known to him.
And the tanks!
Hitler thought bigger was better in every way. He wanted bigger, heavier tanks with bigger guns.
Between that and the German propensity to over engineer EVERYTHING the tank line-up was a mess with too many of the heavier tanks unable to cross most European bridges.
The failure to completely mechanize the Wermacht was a huge failure. Without the trucks and transport needed for the infantry Blitzkrieg was prevented from reaching it’s true potential.
Hitler also delayed the introduction of the ME-262 fighter.
He vacilated between wanting the plane as a fighter only, a fighter bomber and a light bomber. In any event he delayed the introduction for a little over a year.
Hitler was his own worst enemy.