Can't Get the Game

I DID SEARCH THE INTERNET FOR AN ANSWER BUT CAME HERE EMPTY HANDED

So I payed for the game on Switch updated. It cost me 25£. I loved it. 4.99999^/5 stars. But with the bedrock version's redstone I want to move on to the Java Edition. When writing this message it costs 17£ on the offical site. A 8£ difference and there or a 8£ profit for you. I find it is fair-er to be able to sign in and get the game I payed for on a different device. But i can't sign in on the page nor get it to download.

If it is not loggically posiable then please reply and tell me.