Hi,
This means that the account you are signed in to is not the right account where you purchased Minecraft Dungeons.
May I ask which platform you purchased Minecraft Dungeons on?
If you purchased it through the Microsoft Store or the Xbox app, please check your Microsoft account’s order history. Make sure the “Order within” filter is set to 7 years. If you do not see the purchase, please check your other Microsoft accounts as well. You can also check your email for a purchase confirmation or any Minecraft-related emails, including promotions and game updates.
I look forward to your response.
Stay Safe!