Hey, I'm not sure if he is going to be able to play for the u21. He has enough potential, but he has a big weakness in rebounding despite having good stamina and Free Throw.
His secondaries aren't bad, pity about the OD, but he has reasonable secondaries. He is a little tall, so you could have some luck on his training. The rebounding really needs to be brought at least to respectable before starting to rotate between IS, ID and Reb. To go from awful to respectable, you will probably need 7 or 8 weeks, and you can count with some IS or ID pop with the secondary training. It won't be easy, but with some luck, you never know.