Minecraft Windows 10 edition not purchased in store, but is in Xbox companion app

If you have Java Minecraft, sign in with your Mojang Account on the Minecraft Website, and you should get an offer to redeem a code for the Windows 10 Version.

However, it was long ago since I did that, and don't know where exactly you need to go.

After you got your code, you can go to the Windows Store App on your Windows 10 PC and redeem that code in the Store App to get Minecraft Windows 10 Edition.

EDIT: It seems that you need to have purchased the Java Edition before Oct. 19th 2018 to be eligible for getting Minecraft Windows 10 for free.

For more information check this website: https://help.mojang.com/customer/en/portal/articles/2064007-minecraft-for-windows-10

With your Xbox Live player profile, each purchase you make is tied to your account. You can play with friends and show off your maps and skins on any
Pocket Edition or Windows 10 device if they also have an Xbox Live account.
Minecraft Marketplace is available on any Windows 10 or
Pocket Edition device.

All Minecraft purchases are final. For support contact the Store support for the device that made the purchase.

• For Microsoft Store purchases, contact
  Microsoft Support.
• For Apple Store purchases, go to the
  Apple Store.
• For Google Play purchases, contact the
  Google Play Store.
• For Kindle Fire or Kindle Fire TV purchases, contact the
  Amazon Store.

I could not find and download Minecraft Windows 10 Edition in the Microsoft Store app.

Edit: didn't work on downloading the minecraft launcher

Also verify on the windows 10 store, if show you all your purchase ready to install.

Also try to unistall and reinstall the xbox companion app. Regards!

try the xbox companion app instead, not the xbox app but the older companion app, its already installed on windows 10 or if windows 11 can be downloaded from the store, usually works fine that way.