To migrate data to Office 365, your administrator account must have ApplicationImpersonation rights to impersonate the users you are migrating. By default, no groups or users have ApplicationImpersonation rights in Office 365.
Below are two options to grant "ApplicationImpersonation" rights to your Office 365 migration admin account(s):
To grant ApplicationImpersonation rights via the Office 365 Portal:
To grant ApplicationImpersonation rights via PowerShell:
New-ManagementRoleAssignment -Role "ApplicationImpersonation" –User email@example.com
Note: It can take up to 48 hours for these new "ApplicationImpersonation" rights to take effect in Office 365.