Seems like the software and drivers link is broken for the CM2320 as of this morning. I cannot navigate out to the Win 8.1 area to review what drivers and applications are available.
Chances are that your Win8.1 is not compatible with the HP Toolbox software which is often what facilitates the "Send to Computer" functionality while scanning. Most Win8.1 installs that I have seen have removed the useage of the HP Toolbox and replaced it with something else. If that is true and there is no Toolbox then you will most likely not be able to scan documents and send/push to your computer, you must start the scan from the computer and pull the documents instead.
HP Support page for CM2320:
http://h20565.www2.hp.com/portal/site/hpsc/public/psi/home/?sp4ts.oid=3597338