We do not provide the driver. That is provided by QuadTone RIP. What we provide are curves. So, the Install9890-K7.command (did you run that or did you run Install7890-K7.command?) which you downloaded and ran installed our Piezography curves for your use with the QTR driver. All the functions of printing are provided by QTR. But, Page Setups and page sizes are setup by the user. If you are having trouble and need urgent help, I recommend that you write the folks at QuadTone RIP for support of the driver.
First, you should also check that you have the latest QTR installed. The latest versions are:
Mac OS X: 2.7.7
Double check that your Page Sizes have been setup for the 9890-K7 printer.
If QTR can not sort you, it may be a limitation imposed by the OS which you need to sort out. You can also post on the QTR Users Group in case someone else has encountered this. There is a link to that group on the QTR Support Page.