I am trying to use this library. But when I try to import the .zip file (of the directory) downloaded from GitHub, Arduino IDE says "Specified folder/zip file does not contain a valid library"
That's because it contains two libraries, and the IDE doesn't know how to handle that.
Because of this repository structure, you will need to do a manual installation.
Extract the zip file manually and copy the
libraries folder into your Arduino sketchbook folder. You can find the location of your sketchbook folder in the Arduino IDE at File > Preferences > Sketchbook location.