High Priest Prana:
You need the appropriate level and token to become a Human Wizard. To change profession, your level must be at least 20, and to become a Human Wizard, you must have the token that proves that you passed the Test of the Human Wizard.
It seems you have passed the test, but you cannot change profession because your level is lower than 20. If your level is lower than 20, you cannot change profession, even if you have a token. Please come back when you are ready.