Loans store Uplay. (Tom Clancy's Rainbow Six: Siege)

Somebody can explain in more detail how to use these same loans. The campaign will last until 29/08. *If you purchase the standard version of Rainbow Six Siege, the updated version of the "Gold edition" or edition "special Edition," you get store credit in the amount of 899 R. When redeeming a promotional code number of the store credit will be equal to the total amount to be paid. After the purchase, September 7, to your e-mail will be sent a promotional code. Store credit can be used to purchase any product in Ubisoft Store within 7 days of receipt of the above letter. This code is disposable, and the remaining after repayment of the loans will not be available for the next purchase. As I understand it you cannot use them as a discount, if the game is worth more than you got credit?