Hello Pague Tullier,
Welcome to Microsoft Q&A forum.
While Mojang account has been migrated to Microsoft account, the order history and store from the 2 platform remain separated. Your purchase of Minecraft on Mojang before will not be reflected on your Microsoft account and vice-versa. Therefore, Microsoft Store won't show your Minecraft as purchased.
In this case, can you please try to download the Minecraft Launcher from the Microsoft Store or the Mojang website. Log in with your Microsoft account and check if they let you play Minecraft Java Edition?
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