I want to download the latest game update of Treasure of Nadia

If you downloaded the previous version through the website, you should be able to download the updated version now. In order to keep the same save file, you would need to check on the individual game if that’s supported and how.

If you are using the Itch app, then that should happen automatically when the new version is available, or you can click on the specific game and update it manually.

Hope that helps.