From where I can get the Xerox Scanner Management Utility?
I don't seem to have it.
There is no point getting it since it won't help, it is for WSD devices, used here to show that it doesn't add TWAIN or WIA devices, like what Windows Fax and Scan requires.
What you have installed is just putting a template on the printer, so you go to the printer, pick the scan option and scan the file back to the PC. If you want it to work in the very oldschool way of walking to the printer, loading the document, and going back to the PC, opening an application, choosing a device from a list and doing a scan, It will probably be a lot of work
P.S.
If I loose the PaperPort CD, why I must buy it? Why I can't download it from somewhere?
As I understand, when buying the Xerox WorkCenter 3210 I pay also for the software.
For exactly the same reason you have to be anything again when you lose it. If you lose your car key you buy another one, if you lose your phone you buy another one, if you lose access to your Apple ID you lose every song/app/movie you have it associated to. This isn't a case of Xerox being a bully, you paid for a licensed copy of software, not all rights to all software made by Nuance till the end of time.