During your plugin installation, you are able to select where your Audio Content files are stored. These larger files can be installed locally, or onto an external hard drive.
When installing to an external drive, ensure that your drive is formatted to either APFS for Mac computers, or NTFS for Windows.
The plugin files themselves will always be placed in the same default locations:
macOS
/Library/Audio/Plug-Ins/VST/
/Library/Audio/Plug-Ins/VST3/
/Library/Audio/Plug-Ins/Components/
/Library/Application Support/Avid/Audio/Plug-Ins/
Windows
C:\Program Files\VstPlugins\ or C:\Program Files\Steinberg\VstPlugins\
C:\Program Files\Common Files\VST3\
C:\Program Files\Common Files\Avid\Audio\Plug-Ins\
Your Instrument resource files are always installed on your main system drive:
macOS
/Library/Application Support/westwood/
PC
C:\Users\\AppData\Local\westwood\