Please double check our setup documentation - https://docs.zeroqode.com/plugins/aws-file-uploader-plugin
And demo page setup: https://bubble.is/page?type=page&name=aws-uploader&id=zeroqode-demo-02&tab=tabs-1
try reproducing all the setup and document actions, and test them out.
Also would recommend you try, uninstalling and reinstalling the plugin, place a new element of file uploader on page and give it a try.
Lately if everything was set as in our demo/doc method and still getting an error while uploading files, provide some screenshots better a video of you setup and screenshots from browser’s console log (ex:)
Also from current setup, I see you’re uploading file sizes bigger when in our demo, you should check your AWS S3 plan setup which should be able to upload sizable files.