1. Download and install https://tunnelblick.net/cInstall.html
(Select the option to display the icon in top menu)
2. Download certificates from the server
3. Right-click on the .ovpn file and choose Open With Tunnelblick.app
4. Enter the user password you are logged-in with. If this is a surprise, read http://www.macworld.co.uk/how-to/mac/what-do-if-forgotten-mac-password-3594395/
5. Click on Tunnelblick icon top-right
6. A Connect window will be displayed, click Connect
7. At the top Apple menu, click Go > Connect to Server
8. In the Server Address field, type the name of server
9. Enter username and password for your account on the server
10. The directories will be accessible from the displayed window