An error was reported during a file copy step. The file copy step is a wrapper around either xcopy or robocopy (depending on target computer) and an error was reported in its output which may indicate a failed copy.
PDQ Deploy watches for errors to be reported in the output from the copy operation and which will cause the step to fail. The exact details of the error can vary quite a bit, and a check of the output log is necessary in order to see exactly what went wrong.
Examine the output from the copy operating by opening the step details (click on the ## Steps link in the computer list and the the output log link). It's possible that the application is misinterpreting a warning as an error and reporting a failure even though the copy succeeded. If the output from the copy looks okay, please open a ticket with firstname.lastname@example.org so that we can verify the output and possibly make changes to correct it.