Microsoft Store - "Redeem a Code"

I am attempting to purchase the Windows 10 version of the Touchable Pro app from the Microsoft Store, however it states that Touchable Pro is currently unavailable. Here is the URL: https://www.microsoft.com/en-us/p/touchable-pro/9p41l3h6m11k?activetab=pivot:overviewtab
There is an option to redeem a code. Where can I find this code?

Screenshot:
image

Thanks,

Should be available now. Best