Iv just bought the add on, it comes as 8 folders. It is unclear whether I install all 8 separately, whether I need just one, or install on top of each other 

 Mine was just a single folder. There should be a readme.txt explaining what to do?

there is a read.me but as i said 8 separate folders, with different dates.

I also have 8 separate zip files. When I unzip them all only 3 or 4 of the folders actually contain anything. 

Hey guys,
In the zip files, you'll find all available versions. Just install the newest plug-in version (currently "fancy-product-designer-export_1.1.2").