I think this 'suggestion':
// FastLED
CRGB leds[NUM_LEDS];
// FastLED with RGBW
CRGBW leds[NUM_LEDS];
CRGB *ledsRGB = (CRGB *) &leds[0];
was to be read as:
// Original FastLED, remove this line:
// CRGB leds[NUM_LEDS];
// FastLED with RGBW, add these lines in its place
CRGBW leds[NUM_LEDS];
CRGB *ledsRGB = (CRGB *) &leds[0];