To get an existing non-template score to use the VDL sounds, you will need to have installed the XML files (Percussion MIDI Maps) and then load the FIN_VDL Percussion Library to the score. At this point, again, how you procedd will depend upon which version of Finale you are using.
Ted Boliske
Mac OS 10.12, 10.14, 10.15, Win7, Win10 VDL2.5.5, Finale 2010-14.5, Finale 25-27 Kontakt 4-6, various other soft synths