Wix child theme not working

I have created the functions.php and style.css files in another folder and pointed them at wix but it doesn’t work. I’ve tried the exact same code pointed back at the twentyfourteen theme and everything works just fine. What am I missing to make child themes work with wix?

I’d like to change link font colour on some featured content plugin buttons I have on the page and rearrange the header to put the image alongside the heading. I want to go about this the right way with child themes and not have to edit the theme files and be susceptible to updates overwriting my work.

So far just to get a plain background I’ve had to sneakily rename the background image so the code can’t find it as there is no option to remove that either.

Any help would be much appreciated