Hi there
I cannot for some reason buy any royal crystals, when I click on the package I whish to purchase and click buy now nothing happens, I do see in background (behind the royal crys popup) a window appearing but nothing happen.
Anyone had this issue before please assist?
Enable your Steam in-game overlay, that’s what worked for me!
I had this issue before. For me, it was resolved by enabling Steam overlays since the transaction is done partially through Steam integration.
Steam → Settings → In-Game → Enable the Steam Overlay while in-game.
Doesnt seem to work 
It was already on so disabled it and tried nothing, enabled it and tried nothing
In steam, if you right click the game and go to properties → General, there is another place where Steam Overlay may or may not be enabled. If it is on there, then I am not sure what is going on.
Best of luck!