Library Not Found

Hello,

I'm trying to use the following library PixhawkArduinoMAVLink.h and I've added the library via the UI Sketch > Include Library > Add .ZIP Library. I can see that is has successfully been installed.
However when running the example code that it comes with, it says it cannot find the library reference. I can also see that the library is in my documents folder as it should be.

I have a Nano board. Any help would be much appreciated.

// Example Code to read acceleration data from pixhawk
// Check HardwareSerial connection for your Arduino board and connect them according to the connection shown in guide.md

#include <PixhawkArduinoMAVLink.h>
#include <HardwareSerial.h>

HardwareSerial &hs = Serial1;
PixhawkArduinoMAVLink mav(hs);

void setup(){
  Serial.begin(57600);
  while(!mav.begin()){
    Serial.println("Not Connected!");
    delay(1000);
  }
  mav.Stream();
  delay(2000);
}

void loop(){
  float xacc, yacc, zacc;

  mav.ReadAcceleration(&xacc, &yacc, &zacc);
  Serial.print("X: "); Serial.print(xacc);
  Serial.print("  Y: "); Serial.print(yacc);
  Serial.print("  Z: "); Serial.println(zacc);

  delay(100);
}
accel:4:10: fatal error: PixhawkArduinoMAVLink.h: No such file or directory
 #include "PixhawkArduinoMAVLink.h"
          ^~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
exit status 1
PixhawkArduinoMAVLink.h: No such file or directory

Please post a link to where you downloaded the library from.