https://theundefeated.com/features/e...-the-g-league/
How does an elite high school player get into the G League? The prospect must be 18 years old and would have to request a contract from the G League. The G League Basketball Operations Committee would then determine whether the prospect is good enough to play in the league. That means the league wouldn’t sign a player unless that player is deemed talented enough. If the answer is yes, the prospect would be signed to a contract and entered into the G League draft.