You are unable to complete the onboarding process for Exclaimer Cloud, or the Office 365 connector setup wizard. Multi-Factor Authentication (MFA) is enabled for your Office 365 users.
Multi-Factor Authentication is a method of verifying who you are, above and beyond a username and password. Using Multi-Factor Authentication for Office 365, users are required to acknowledge a telephone call, a text message, or a smartphone app notification, having correctly entered their password. Sign-in is only possible after this second level of authentication has been confirmed.
To complete required setup for Exclaimer Cloud, you must specify credentials for a global administrator account, and a series of PowerShell scripts are executed. If the global administrator account requires Multi-Factor Authentication, these scripts will fail.
To complete the Exclaimer Cloud setup, you will need to configure an app password to use when prompted for the Global Administrator credentials in the wizard.
To create an app password please follow the guide here.