Hi Anton,
Sorry for the confusion. Both versions are supported.
I will manually add an order for you so you can download the business edition if that's what you needed.
I will try to make things more clear to avoid that for future customers.
3.1.9 is an update for 3.1.8 due to joomla framework change. Otherwise it's the same as 3.1.8.
Anyway, sorry again for the confusion, I thought I made it clear on the landing page, but I didn't.
Kind regards,
Deian