Hi Dave. The libraries you install via the
Arduino IDE Library Manager, or via the IDE's "
Add .ZIP Library..." feature are installed to the "libraries" subfolder of the sketchbook folder. This is also the folder you should use when
manually installing libraries.
You can find the location of the sketchbook folder by selecting "File > Preferences" from the Arduino IDE menus, and then checking which path is shown in the "Sketchbook location" preference.
C:\Users\me\AppData\Local\Arduino15\libraries
However, that folder is only used by that "built-in" library installation feature, and Arduino IDE will not use that folder for any other library installations. You should not use that folder for the installation of additional libraries. Use the "libraries" subfolder of the sketchbook instead.
Regards, Per