@metalm3 You have to install and activate it as normal theme along with Jevelin theme.
You will find more information about child theme on the following page.
Also to help us keep support thread separates could you please create your own thread for your question instead of replying on others thread as it makes the thread messy and hard to read.
If you want to you can also add reference of this thread in your newly created thread.
We would be more than happy to help you on your new thread.