Hi Rachael
The person to receive the notification needs to have this permission
Get a notification message when an attempt is submitted
mod/quiz:emailnotifysubmission
If you use groups then the teacher needs to be in the same group (or have the viewallgroups permission)
I believe this isn't limited to manually graded quizzes so you may want to assign this via a separate/additional role or permission override so that your trainers don't get notifications
https://totara.help/docs/list-of-email-notifications
NB we had some inconsistency with testing these notifications this week, if we find the root cause I'll try and update with more detail in this thread.
Hope that helps
Stewart