If you want to migrate Zimbra file to Office 365 account then you can try any commercial software like KDETools Zimbra to Office 365 Migrator.

Features such as:

This application migrate Zimbra file to Office 365 and Exchange Server account.

This application shows a preview of Zimbra emails, contacts, calendars, briefcase, and all before conversion.

This application maintain folder Structure during the migration process.

Read More: https://www.kdetools.com/zimbra/office-365.html