Windows GUI applications do not typically take their input from standard input, so this won't work. You could probably do this with Win32::API, but even though Perl is my favorite language and this is perlmonks.org, in this case I would recommend AutoHotKey, as it makes this sort of interaction stupidly easy, and you'll find a lot more documentation and examples online.

Untested.Tested.

^F5::
run, CreateFile.exe
WinWaitActive, CreateFile, ,2
if ErrorLevel
{
    MsgBox, WinWaitActive timed out.
    return
}
else
{
    send, {Enter}
    WinClose
}
return
[download]

Note that WinWaitActive expects the window title, which is not necessarily the same as the executable. You can match on other criteria as well.

Run the script, and then you can trigger the execution/Enter/close at will with Ctrl-F5. There are other activation methods you can use, but the hotkey approach is easy to debug. I also changed your logic to wait 2 seconds for the window to activate, rather than just sleeping for 2 seconds and hoping for the best, but this is just an example to get you started.

AHK Documentation