Dave,
Here are my thoughts...
1.? I put them in C:\Arduino1.8.7\hardware\teensy\avr\libraries and now have it working after having some compile trouble.? See my other post with details...?
/g/JackAl/topic/new_document_file_installing/29417438?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,294174382.? I would imagine installing the teensy add on software and selecting the teensy3.6 as the target board in the IDE has something to do with this.
Jim KM4TXR