Error Pop up keeps popping up

So my girlfriend got a Google play reward, that she could get a month free subscription of nitro, but after she bought that, her discord couldn’t process the order and said; oh no! Something went wrong with your purchase, try again later. 
But when she clicks oke, it keeps coming back.

Here is wat we already tried: Downloading the app on another device, weirdly enough no issues there no pop up nothing. Tried downloading the app through a different Google play account, no luck still the pop up. Clearing cache and deleting the data from the app, again no luck. 

Also discord support will not help us, and says they can’t do anything about it.

Someone any ideas please help.