Does FullContact work with Apple’s two-step verification?
Yes. If you have two-factor authentication or two-step verification enabled on your Apple account, you can sync iCloud with FullContact using an app-specific password.
To create an app-specific password:
1) Go to https://appleid.apple.com/ and sign in.
2) Scroll down to Security, then click Generate Password under App-Specific Passwords.
3) Create an app-specific password for FullContact.
4) Copy and paste that password into the password field on FullContact when you connect your iCloud account.