To upload the authorization letter for the toys category to Amazon, you can follow the general steps below:

1. Log in to your Amazon Seller Central account;

2. Find the "Inventory" option in the top navigation bar and select "Add a Product";

3. Enter the name of the toys category you want to sell in the search bar and click "Search";

4. Find the specific toy product you want to sell in the search results and click "Select";

5. On the product information page, check the "Key Attributes" section to confirm that all requirements for the category are met;

6. Find the "Apply to Sell" button at the bottom of the page and click it to enter the access application page;

7. On the access application page, find and select the "I will be providing an authorization document" option;

8. Prepare the complete toy category authorization document according to Amazon's requirements. This may include supplier authorization letters, manufacturer authorization letters, brand authorization letters, etc. Specific requirements can be found on the access application page;

9. Click the "Continue" button and upload the authorization file as prompted on the page. You can directly drag and drop the file to the designated area or select the file to upload;

10. After completing the file upload, follow the instructions on the page to confirm your information and submit the access application. The Amazon team will review your authorization documents. Usually, they will respond to your application results within a few working days. Please make sure that the submitted documents meet Amazon's requirements to increase the chances of passing the review. If necessary, Amazon may ask you to provide more additional documents or information.

Please note that the above steps only provide general guidance, and the specific process may vary slightly depending on the region and account type. It is recommended to refer to the documentation of Amazon Seller Center or contact Amazon Customer Service for more accurate guidance and help.

In addition, if you are a seller with a registered brand in your store, when submitting the review materials, according to Amazon's requirements, if you choose "retailer/distributor", you need to provide invoices and product packaging pictures; if you choose to be a "manufacturer" or "both", you usually only need to provide product packaging pictures. But no matter which option you choose, the packaging pictures generally need to include information such as the manufacturer's name, address, and product model.

If you encounter problems during the upload process, such as the file size exceeds the limit, you can compress the picture, but be careful to ensure the clarity of the picture. If the application is rejected, you can make corresponding adjustments and improvements based on Amazon's feedback, and then submit the application again. Or try to communicate with Amazon customer service, explain the situation and seek more detailed guidance.