The Sketch > Include Library > Add ZIP Library installation method requires that the library be located in the root of the .zip file. Unfortunately that is not the case here so you will need to do a manual installation:
- Copy the folder FPS_GT511C3 from the downloaded file to the libraries subfolder of your sketchbook folder. You can find/change the location of your sketchbook folder in the Arduino IDE at File > Preferences > Sketchbook location.
- Restart the Arduino IDE if it's running.