Did you read this from the Google Play store when you added it to your phone . Unfortunately I can't help other than what I posted below .
Description
iNotes is an easy notes app for synchronizing your notes of Android to Notes app on Mac/iOS(iphone, ipad) . It is currently applicable to iCloud, Gmail,Yahoo, Aol,163 only.
To sync with your email, you need to add your Email account first on the settings, then your notes will be synchronized to your email under the label 'Notes'.
Important Instructions:
1. If you sign in iNotes other than iCloud, you must enable your Notes on iOS (Settings>iCloud>Notes), otherwise, the notes will be not synchronized.
2. The password is the same as your email password;
3. If you are not allowed to sign in, it is probably your email account is not applicable to iNotes. Only iCloud, Gmail, Yahoo, Aol, 163 are allowed.
4. If you are using an email account dominated by google, you can click ' Google Apps' to authorize.