It is not in vst3 folder. You have to find "HalionSonic.dll" file. For 32 bits version, try in Program Files (x86) in windows 7, vstplugin folder or Steinberg/Halion Sonic Folder. After installing Halion Sonic.dll in Cantabile, if you want to play in GM mode, you have to go in "Options" and check Gm mode. Use LoopMidi out in vArranger and LoopMidi in in Cantabile.