Download Lync for Mac 2011 for Office 365 Users
You may already know that Office 365 E3 and Small Business Premium includes the full office desktop suite for Windows and Mac for up to 5 devices per user (here), and therefore includes Lync for Windows and Lync for Mac 2011.
You can download Lync for Mac from this page (ensure you are appropriately licenced):
Click “Buy Lync for Mac 2011” for a direct download link (not a link to buy oddly)
Link: http://go.microsoft.com/fwlink/p/?linkid=236302 which prompts you to download from here:
Ensure you also have the latest update: