Well this is a TL about German WW2 victory so lets put Hitler's/Germany's mistakes in a list:
Feel free to add things.
- Hitler believed he could persuade the UK to join Axis even when they got to war with him, his obsession let him to let them walk out of Dunkirk, lose the Battle of Britain and invade the Soviet Union to prove them the German strength in hopes that the UK would agree to submit.
- Feared to lose more troops after the massacre in Crete, so he let Malta and Cyprus to remain British, leading him to lose the North African front.
- USSR rushed invasion, do i need to say more?
- Didn't give enough support to Rommel and Afrika Korps
- Alienating the USA by supporting Native American freedom instead of National Socialist White parties there.
- When Barbarosa began the Russians show the Germans as liberators, if the Germans had not tried to kill everyone, they would have earned the Soviet people's support, who already hated Stalin, instead with the things the Germans did, they just show Stalin as a lesser evil.
- Sending his whole fleet plus parts of his aiforce to destroy the junk ships the British send to rescue their troops in Dunkirk, thus eliminating the British proffesional army and dealing a crippling blow to the British Empire.
- Not trying to kill every Slav in the USSR and instead act as liberators from the evil commie regime is a good solution.
- He could ally with Greece to kick the British out of the Mediterranian Sea.
- Supporting National Socialist groups in the USA, just NOT (only) Native Americans.
- By occupying Matla and Cyrpus, he could easily establish Naval Supremacy in the Mediterranian Sea and kick out the Brits, additionally allying with Greece might made that lot easier.
- Thus he could allocate more resources to Rommel and the African Korps that would reach easier the African Korps, since the British Navy would have already be kicked out of the Medditerranian Sea, thus Egypt would be an easy target and would have fallen.