Setting up OpenVPN on a Mac
Download TunnelBlick
https://tunnelblick.net/release/Tunnelblick_3.8.4b_build_5602.dmg
Right click (or CTRL + Click) the icon and press Open
Once installed you can open it from the top icon
Click VPN Details. You can drag the OVPN file from the Config Files into TunnelBlick (should be sent directly to you)
When you connect, you will need to enter the username and password supplied.
Once connected, go to Finder and Connect to Server
And enter the details to connect to your Server
You may be asked your network credentials, this is separate from the the VPN credentials and will most often be the same as you log on with on the network or your machine if supplied by the company.