Do this and you will have mango seedlings in one week. First remove the seed from the fruit, then cut the seed cover from its fibery side, then open the seed cover and take the seed out and lastly plant the seeds in a pot. Don’t over water the seeds they easily rot.
I have three mango tree grown from seeds 5 years later they have flowers. I didn’t graft them, they are totally from seeds. Their 5th year they bloom and have fruits, that’s the first time I have harvested around 20 fruits from my mango tree.