Make sure both apps are running when you schedule your meeting, and you are all set! If you have an older version of either app, click Check for Updates on the Help menu of the respective app.

You also need Skype for Business on Mac version 16.13 (from December, 2017) or later. To get started, install Outlook 2016 for Mac version 1000. Until that time, on-prem users can schedule Skype for Business meetings in the delegator's calendar, but the meeting will be set up using the policies and join information of the delegate, not the delegator. Support for delegate scheduling by Skype for Business 2015 server users will be available in a future server update. Note that this is for Skype for Business Online users only. The online meeting will be set up using the delegator’s policies and join information. When using the latest release of Outlook, a delegate can create or edit a meeting in the delegator's calendar and make it a Skype for Business meeting. With today's release of Outlook 2016 for Mac, Skype for Business Online users on a Mac who are configured as delegates can schedule Skype for Business meetings on behalf of their delegators.

Delete skype for mac user settings