No, you should upload a single file. It should be the largest, highest quality version of the file you have, as a JPEG or TIFF. The creativehub web app will automatically resize the file to the optimum resolution for each print variant you have created, and will print it when you receive an order. The file will not be cropped so all the variant sizes will be the same aspect ratio as the original file.
You may want to color manage your file, by tagging it with the right color profile for the paper and print type of your product. Click here to learn more about color management.