Thanks to all for your help and some research which gave me more of an understanding regarding VST2 and VST 3 I have finally managed to sort this. For anyone having similar problems this is what I did.
1. Realised that Finale, as some others have said, can only recognise Vst 2.
VST 2 have the extension .DLL and VST 3 normally have the VST 3 extension or just none.
2. Realised that the Vienna assistant on install was not putting them where I had specified.
3. Looked at some helpful guidelines as to where the .Dll (VST2 files) might be on Windows pc and checked them all. Mine were not in these but armed with the knowledge of what to look for I found them (shown at the bottom of the other suggested places)
C:\Program Files\VSTPlugins
C:\Program Files\Steinberg\VSTPlugins
C:\Program Files\Common Files\VST2
C:\Program Files\Common Files\Steinberg\VST2
32-bit plug-ins on 64-bit Windows: C:\Program Files (x86)\Steinberg\VstPlugins
Mine were actually in this path
C:\Program Files\Cakewalk\Vst plugins