In order for the Child Theme option to be available, there has to be a child theme existing and active in WordPress already. J.E.D.I. does not create a child theme automatically, so that has to be added first. You can use any simple or blank child theme, it doesn’t have to be a premium child theme or anything like that. But the folder and files need to be there.
If you need help setting up a child theme, there are a couple options for you…
We have a blank child theme available for download here: https://www.ferventsolutions.com/downloads/simple-divi-child-theme/
Create your own customized child theme on Divi.space: https://divi.space/divi-child-theme-builder/
Use a plugin to create a child theme as explained in this tutorial: https://quiroz.co/5-easy-steps-to-creating-a-child-theme/