Problem with uploading files on remote server

Hi all.

I’ve set up a basic file upload page using the Uploading Single File To Your Server tutorial.

This works fine on my local machine, however it fails to work after I deploy it (using Docker) to an Ubuntu instance on my AWS server. I’m guessing this might have something to do with folder permissions, but I can’t find any information on it.

Does anyone have any suggestions what I can try? I find working with AWS completely non-intuitive, so any guidance would be welcome. Thanks.