Update: File Transfer for users homed on Office 365 has been released. For more details see this article: Skype for Business on Mac April update is here - and File Sharing during chat for Office 365 ...
Updated Apr 25, 2017
Version 2.0
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How can I transfer files on Skype for Business mac?
I have the latest version (16.13.181) and there is no way to do it yet...