High Priest Sylvain:
You need the appropriate level and token to become a Cleric. To change profession, your level must be at least 20, and to become a Cleric, you must have the token that proves that you passed the Test of the Cleric.
It seems you have passed the Test of the Cleric, 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.