I think that there is a bug in the program. I presume that you downloaded and installed all of the free synths and sounds etc. under the Help tab.
Click on the + at the left to select an instrument. Select a Vita instrument, it doesn't matter which one. Pianos are not shown. When the Vita 2 Instrument editor comes on the screen, click on the down arrow to the right of the instrument name and you will see the entire list of Vital instruments. Vital acoustic pianos are there.