ho to integrate libraries

Hi I downloaded

an now i Have the problem that headers are missing like

#include "compiler.h"
#include "clock.h"
#include "gclk.h"
#include "pinmux.h"

how do I get the "right" Prototypes and Program files?

You need their implementation of the Amtel Software Framework : GitHub - adafruit/Adafruit_ASFcore: ASF core files for Zero