Purchase not compatible with devise

My son bought a new world - one block sky block - and accompanying other stuff to go with it. He bought it multiple times trying to get it to work - he is 5 and used his amazon coins, about $6 worth - but it is not compatible with his device, an Amazon tablet. Why would a purchase be allowed to go through when it is not compatible to the edition on the device?

 

I chose random version and platform because I frankly do not know. Just want some answers and would prefer a refund, but you do not do that, from what I see. Need to stop this from happening again.

 

It is like stealing candy from a baby.