On the apple menu ,located in the top-left corner of the screen click on System Preferences
And then click Network
In Network window click on the + symbol to create a new connection.
Next in the dropdown menu select interface as default then choose VPN Type as L2TP Over IPSec then click on Create
Server Address : one of the zebravpn address (it will be found in client area)
Account Name : It's zebravpn username for Entering password and secret click on the Authentication Setting
Enter password and secret (secret and password will be found in client area)
Click on apply to information be saved.
Then as last step click on Connect for connecting to server.