How to set Prestashop for not generating an invoice when the order is at 0?

[kapi]

Hello!

 

In my store I have products and what we call FREEBIES. So the freebies are free. But to grab a freebie, I want the visitor to create an account... then to be logged (for marketing purposes).

 

I have then enabled the possibility to have orders at 0 in order to avoid an error at the last step of the "purchasing" process when you add the freebie in the card.

 

BUT I don't want PRESTASHOP to issue an invoice (and to create the database in the database when the order is at 0... only to send the download links as it's done for any product. How to process?

 

Or perhaps there's another solution to perform what I want to do...???

 

Thank you very much for your help.