Install the Tunnelblick program. For Mac OS X 10.9 and 10.10 it is necessary to install Tunnelblick 3.4 or higher or it won't work correctly.

Unzip the zip file found in your user's home in the VPN folder in other directory and add the extension .tblk to it.

Open that directory which now will be recognized by Tunnelblick as a VPN configuration.

When asked if “Make configuration available to all users” choose «Only me». Introduce your user and password in the system.

In the applications menu open Tunnelbrick.

In the indicator panel, push the Tunnelbrick icon and choose VPN details….

In the configuration, choose Use DNS and in the dropdown Set DNS/WINS.

If the Tunnelblick version has this option, choose OpenVPN 2.4 or greater. Versions 2.3.x are not working with this setup.

In the application menu, open Tunnelbrick if not open already.

In the indicator panel, push in the Tunnelbrick and choose Connect vpn-citius.

Introduce the username and password of your CITIUS account.

If you receive a warning about the public IP address, you can safely ignore it.