How to use remote access on Macbook Pro?

I have a Macbook pro with which I am trying to access a remote desktop from a secure website. Unfortunately whenever I attempt to connect to the desktop I get the following error message:
Your OS/platform is not supported for this component.
The website/remote access is provided by Juniper Networks. Does anyone know of a solution that is not going to need a Windows OS installation?

Thank you in advance.

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia��).