After downloading Skype for Business for Mac, you will want to sign-in.
In the Dock, click the Skype for Business icon () to open the app.
Enter your sign-in address (for example, email@example.com) and password, and then click Sign In.
Tip: If you don't want to enter your password each time you sign in to Skype for Business on Mac, select the Remember my password check box.
If you are asked for both a user name and a sign-in address, click Advanced Options. If you are a Skype for Business Online user, use firstname.lastname@example.org. Otherwise, use domain\username, and then click Sign In.
You are now ready to start using Skype for Business on Mac. To join a meeting, see Join a Skype for Business meeting.
Sign out of Skype for Business on Mac
On the menu bar, click Skype for Business, and then click Sign Out.
After you sign out, you cannot send or receive messages, and you appear offline to other people.