Package 'appindicator3-0.1', required by 'virtual:world', not found

[Nocturna22]

Hello, i got some serious Problems.

humanity@0-Milky-Way:~/Programme/g510s$ make
cc  -fcommon -Wall `pkg-config --cflags gtk+-3.0 appindicator3-0.1` -c g510s.c -o g510s.o
Package appindicator3-0.1 was not found in the pkg-config search path.
Perhaps you should add the directory containing `appindicator3-0.1.pc'
to the PKG_CONFIG_PATH environment variable
Package 'appindicator3-0.1', required by 'virtual:world', not found
g510s.c:26:10: fatal error: gtk/gtk.h: Datei oder Verzeichnis nicht gefunden
   26 | #include <gtk/gtk.h>
      |          ^~~~~~~~~~~
compilation terminated.
make: *** [Makefile:4: g510s.o] Fehler 1

There are more dependency problems. I managed to fix them all, just to let the compile fail once again. So i deleted everything. Above is the first error without modifying anything.

This is the latest error i got, after trying hard to fix the problem.:

cc  -fcommon -Wall -c g510s-keys.c -o g510s-keys.o
g510s-keys.c: In function ‘process_keys’:
g510s-keys.c:114:14: error: ‘G15_KEY_PLAY’ undeclared (first use in this function); did you mean ‘G15_KEY_L5’?
  114 |   if ((key & G15_KEY_PLAY) && (key & G15_EXTENDED_KEY)
      |              ^~~~~~~~~~~~
      |              G15_KEY_L5
g510s-keys.c:114:14: note: each undeclared identifier is reported only once for each function it appears in
g510s-keys.c:114:38: error: ‘G15_EXTENDED_KEY’ undeclared (first use in this function)
  114 |   if ((key & G15_KEY_PLAY) && (key & G15_EXTENDED_KEY)
      |                                      ^~~~~~~~~~~~~~~~
g510s-keys.c:122:14: error: ‘G15_KEY_STOP’ undeclared (first use in this function); did you mean ‘G15_KEY_L5’?
  122 |   if ((key & G15_KEY_STOP) && (key & G15_EXTENDED_KEY)
      |              ^~~~~~~~~~~~
      |              G15_KEY_L5
g510s-keys.c:130:14: error: ‘G15_KEY_NEXT’ undeclared (first use in this function); did you mean ‘G15_KEY_LIGHT’?
  130 |   if ((key & G15_KEY_NEXT) && (key & G15_EXTENDED_KEY)
      |              ^~~~~~~~~~~~
      |              G15_KEY_LIGHT
g510s-keys.c:138:14: error: ‘G15_KEY_PREV’ undeclared (first use in this function); did you mean ‘G15_KEY_MR’?
  138 |   if ((key & G15_KEY_PREV) && (key & G15_EXTENDED_KEY)
      |              ^~~~~~~~~~~~
      |              G15_KEY_MR
g510s-keys.c:146:14: error: ‘G15_KEY_MUTE’ undeclared (first use in this function); did you mean ‘G15_KEY_MR’?
  146 |   if ((key & G15_KEY_MUTE) && (key & G15_EXTENDED_KEY)
      |              ^~~~~~~~~~~~
      |              G15_KEY_MR
g510s-keys.c:154:14: error: ‘G15_KEY_RAISE_VOLUME’ undeclared (first use in this function)
  154 |   if ((key & G15_KEY_RAISE_VOLUME) && (key & G15_EXTENDED_KEY)
      |              ^~~~~~~~~~~~~~~~~~~~
g510s-keys.c:162:14: error: ‘G15_KEY_LOWER_VOLUME’ undeclared (first use in this function)
  162 |   if ((key & G15_KEY_LOWER_VOLUME) && (key & G15_EXTENDED_KEY)
      |              ^~~~~~~~~~~~~~~~~~~~
make: *** [Makefile:13: g510s-keys.o] Fehler 1
humanity@0-Milky-Way:~/Desktop/g510s (1)$ 

Now i don't know further.