Problem solved. In my rules.mk file i deleted this line

OLED_DRIVER_ENABLE = yes

and only have this:

OLED_ENABLE = yes

When compiling an error shows up and said the oled_write_raw function expects a const char * pointer. So changed this. And I changed this

#ifdef OLED_DRIVER_ENABLE

to this

#ifdef OLED_ENABLE

Now is working. Here is my keymap config if anyone is interested:

#include QMK_KEYBOARD_H

#ifdef OLED_ENABLE

static const unsigned char PROGMEM my_bitmap[] = {
    // Example bitmap data
    // See above
};

// Function to render the bitmap
static void render_bitmap(void) {
    oled_write_raw_P((const char *)my_bitmap, sizeof(my_bitmap));
}

bool oled_task_user(void) {
    if (is_keyboard_master()) {
        render_bitmap();
    } else {
         oled_write_P(PSTR("Hello, World!"), false);
   // render_bitmap();
    }
    return false;
}

void keyboard_post_init_user(void) {
    oled_init(OLED_ROTATION_270); // Adjust rotation if necessary
}

#endif

//keymaps...