To migrate from a Google Apps or Gmail account, these steps MUST be followed:
Go to
https://admin.google.com and authenticate as a domain administrator.

Click on Security

Click on Show more and then Advanced settings

Go on Manage API client access

Client name: 794841909041-4ujv1ss1o7m7kqm3gtqd06bklietmmde.apps.googleusercontent.com
API scope:
https://mail.google.com/,https://www.googleapis.com/auth/contacts.readonly,https://www.googleapis.com/auth/calendar.readonly,https://www.googleapis.com/auth/admin.directory.group.readonly,https://www.googleapis.com/auth/admin.directory.user.readonly,https://www.googleapis.com/auth/drive
If you are using a free gmail.com account, then you will need use the individual user name and password for each account. OAuth
2.0 challenge requires this in order to authorize
MigrationWiz access. After submitting a migration for
mailbox(es), MigrationWiz will send an email to each user mailbox in
order to ask for access privileges. Once the user confirms access
privileges then the migration will begin.