Free shipping based on Customer group

Hi All,

I have searched forum but was not able to find an answer on my question. I have Open cart Version 2.0.1.1 that comes with a monthly service that I'm paying to a third party. This does not allow me to install any extention, so I have to find the files and codes to change myself if I want to customize a bit.

The idea is to create a Customer group named ''Free shipping'' and to set Opencart to allow Free shipping for this group only.

Thank you for your help

So this service doesn't allow you to install extensions, but allow to modify core files?