trial account asking for registration code

my son wants to play FF14 with me but i didnt want just straight up buy him an account without him trying it out first and i dont want him messing around on my account either so i tried to create him a trial account, i went to the trial website got the launcher installed the game on his pc but after i created him an account it keeps asking me for a registration code as if i bought the game

how am i supposed to use a trial account without the need of a registration code which you only get for buying the game? i tried exiting the launcher and logging in but all i get is an error saying i dont have an active subscription