To sync your Apple email address to your Itemize account, please visit the link provided and follow the steps under "Generate an app-specific password", https://support.apple.com/en-us/HT204397.
You will first be prompted to sign in using your Apple ID and password. You will then have to enter the security code sent to your mobile device. Following step 2 on the list, you will scroll to the Security section where you will generate an app-specific password.
After you have generated your app-specific password, log in to your Itemize account and follow the below steps to connect your email address to start syncing your digital receipts:
1) Go to the menu in the upper left-hand corner of your device
2) Select 'Settings'
2) Tap on 'Connect Email'
3) Select 'Other'
4) Select your domain address (ie: icloud.com)
5) Enter your username and app-specific password
6) Click 'Submit'