Ok, first of, why should I (as an institution) care about the people unable to fulfil the conditions of my test? Maybe I only want people with a basic understanding of file formats because chances are they will have less issues with future applications?
> They did need to provide detailed instructions ahead of time, including possible issues with unsupported formats.
They send out a message a week before the tests. The website only accepted the allowed formats. You could complain about them using Twitter to send out that message but you are not.
> They didn't need to accept heif files. They did need to provide detailed instructions ahead of time, including possible issues with unsupported formats.
They did not accept .heic files (see the source from the upload js file). They did provide a list of supported files. Maybe the handholding should stop at some point?