Minecraft.net says i dont own the game

Minecraft.net says i dont own the game. I wanted to change from Minecraft Windowns 10 to Java Edition but it doesnt even recognize that I bought the game at all. I searched now in forums for over 3 hours and I am completely lost. Its all totally confusing. I dont even know if I now need to buy Java edition aswell but it doesnt even exist in the windows store as such.

Please help me I paid 50 Euro for this.