Bonjour William !
A teacher could upload his credentials (diploma or certificate related to education, an MBA in another field is not accepted) when Italki opens the gates for application for teachers.
When the gates are closed, you can only apply as a tutor (and offer less choice of lessons).
You have the case of a couple: they are both qualified but the husband couldn't apply for teacher and he's waiting to be accepted as a teacher, he's still a tutor... While his wife applied few months before as a teacher and got accepted by italki...
Bonne journée !