You use locally installed Agent for Office 365. After enabling multi-factor authentication(MFA) for your Office 365 organization, global administrator credentials are not accepted by Agent for Office 365.
Either the credentials are incorrect or the specified user is not an administrator in Microsoft Office 365
You want to use Acronis Cyber Infrastructure Backup Gateway to connect storage backend to Acronis Cyber Cloud. You have two-factor authentication (2FA) enabled for the cloud tenant where you want to register this storage and this tenant's users.