If a user in your account is having trouble logging into ignite, it's often because they've been invited but they haven't activated their account yet.
When a user is invited but does not activate their account from the invite email, they will not be able to create or reset their password from the login page. So if a user in your account reports that they've tried resetting their password or self-registering but never got their reset password email, check the People tab to see if their status is "Invited". If so, reinvite them so they can activate their account.
This commonly occurs when a user who was invited to both ignite and a review tries to start the review before activating their account.