If you want to convert Zimbra to PST then you can use KDETools Zimbra to PST Converter tool. Features are:

• It is easy to convert Zimbra files into PST without losing data when using this advance software.
• This application also support directly conversion of Zimbra to Gmail Converter and G Suite, Google Drive etc.
• This application easily convert Zimbra to Office 365 and Exchange Server account.

Read More: http://www.zimbra-converter.com/