Cannot access files in library

I have a new install of Arduino created using zip file.
My problem is that I cannot access library files.
copy of sketch below showing files I need.
self balance sketch
when I compile this it says file not found.
The needed files are in /arduino/libraries
When in the sketch when I go to file/sketchbook It shows nothing.
If I go to file/preferences I shows my sketchbook file with a copy of my last sketch.
I checked preferences.txt and find the correct path
self balance pref
what am I missing?

What files are 'missing', it does tell you, have you installed the libraries using the library manager?
Post the FULL error you get using the 'copy error messages' button on the IDE.

The libraries are downloaded from authors site. How do I use library manager for custom files.

Library manager was key. When I uploaded the author's zip file using library manager it worked. Thanks

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