You might take a look at this, a woman in Phoenix, Arizona grew mango trees from seed and 15 years later they are now huge trees.

https://www.youtube.com/watch?v=jd122RCGySg

The reason the one in the top video had a growth "spurt" but stopped growing, is that it used the energy from the seed to grow, then , after about 2 sets of leaves, it runs out.

mango is very easy from seed, at least for the first 2 sets of leaves because it uses the energy from the seed. as long as it has water touching the roots.

i have thrown mango seeds in my worm bin with the lid on, completely dark, and pulled live seedlings with leaves from the bin.

after this point it needs sun (bright light) and fertilizer. personally, i dont like chemical fertilizers, especially on a plant this size, its very easy to burn the roots, so i just use compost, or rich soil... No one fertilizes the forest, and plants seem to grow quite nicely there.

slowly acclimate seedlings to full sun over a period of days or weeks. (1 hr per day, then 2, etc...)

mango seedlings are fairly sturdy little guys in this respect though. i have put them in full sun right away and they lived, but i dont recommend it