Same issue here. Apple please fix this!!!!!!

Redemption codes are are only valid in the country of origin of the apple business account that 'buys' them. So if your apple business manager account is created using a German address and DUNS number, the codes will only work in Germany. It's absolutely ridiculous and really poor from Apple. But that's how it works. If you want codes to work in a certain country, you have to have a business in that country and create separate apple business manager accounts for each country that you want codes for.

I am also having this problem - the download link for the redemption codes does not appear not matter how long you wait or refresh screen, and they're not visible in the purchase history. We called Apple business manager support and got transferred to many different departments and none of them even understood what a redemption code was. Really frustrating. Anyone else had any luck getting help from business manager support on this issue? Our company app relies on these codes being available!