Hello,
I would be happy to help clear up any misunderstandings. The way you are currently trying to upload changes is not the intended method, which is why it is not working.
Here is a tutorial you can follow to learn how to suggest new notes or changes. The process is essentially the same for both.
Tutorial: How to suggest a change to AnkiHub
While the tutorial demonstrates how to suggest changes for the AnKing Step deck, you can apply the exact same steps to your own deck.
Please note that you can only suggest changes for a card if it still uses the same note type as the one on the AnkiHub website. Generally, you can only upload new cards if they match the note type of your AnkiHub deck. If you would like to add a new note type to your AnkiHub deck, you can follow this tutorial: How to add a new note type to an existing deck on AnkiHub
Let me know if you need help with anything else 