There are multiple "Library" folders on your Mac. Your Spectrasonics sounds are stored in your User Library. By default, your User Library is hidden. (If you have your STEAM or SAGE folder stored on an external drive, there will still be an Alias in this location). In OSX 10.10 (Yosemite) and above, you can now show the User Library.

Follow the steps below to show the hidden User Library folder:

Open a Finder window, and navigate to the "Go" menu in the top left corner of your screen.

Select "Home" as shown in the picture below:

Then select View Options (Command-J) from the View menu. From the View Options window, select 'Show Library Folder'

The User Library folder will now be visible in the Username (home) folder, as well as in the "Go" menu.