To safeguard your account, you would need to verify your email in order to access all app features, e.g. managing account, downloading manga, creating a backup.
However, your account may be linked to an incorrect email or an old one that you are not able to access anymore.
In this case, please contact our in-app support center or email email@example.com. Let us know the currently-linked email of your account and the preferred email. Our agents will assist you ASAP.