Minecraft download no longer works?

Re
1

So I bought Minecraft and played it for a short while, on a Windows computer that is now broken. Now I have a MacBook and wanted to download Minecraft with the same account with which I bought it, but that didn't work because I supposedly did not have it and would have to buy it again. However, my sister was able to switch from Windows to Mac with the game without any problems. Support doesn't help me. (And before any kids think that Mac is not a PC to play with, you can leave the comments, it's ultimately my decision with what games I play). I wonder why I would have to buy the game again even though it is definitely the same account with which I already bought it.

Co

Which edition did you buy?