Why does Downloaded file not run with Digital Editions 4 after being downloaded

My computer is an Apple pro Note Book running OX 10.9.

While running Adobe Digital Editions 4 to download a file size of 132mb after a few  minutes an error file appeared with a large amount of data which also indicated that a copy was sent to Apple. While the downloading was taking place there was no indication in the small window showing the progress of the downloading. I checked and found the file had been downloaded (132mb). But it would not run.

I downloaded another two much smaller files which both are ok.

I contacted the supplier and they managed to download the file and run it.

Question: Any suggestions as to what might be the problem?

Les