How to put upload secure folder outside J folder?

I'm trying to setup my first Hikashop & will only be selling digital downloads (.zip files).

The documentation says:

Upload secure folder : Folder in which the products files will be uploaded to.
We recommend to put this folder outside your joomla installation folder. That way, if your website is hacked, you have more chances that the products files won't be changed. By default the folder is inside the Joomla installation folder but protected with an .htaccess to prevent access via the web. Only possible access will be via FTP,SSH or PHP.

Can someone explain HOW to set this in HikaShop?
On my server, I have Joomla installed:
public_html/root/

I have my digital download files in:
digitial-downloads/ (It's not even inside public_html/)

In Hika Config, the option only seems to use folders relative to Joomla's root installation folder.

Thanks for your help