Creality V2.2 and DGUS LCD Config (1 reply)

I want to build Marlin from scratch for my setup which is an FYSETC DGUS LCD and my Creality V2.2 motherboard (MEGA2560)
I bought LCD here: [www.aliexpress.com]

I'm using Marlin V2.1.1 but when I uncomment "#define DGUS_LCD_UI_FYSETC" I get a compiling sanity check error stating "Serial Port 3 pin D14 and/or D15 conflicts with another pin on the board."

What is wrong?

P.S. I'm using this hardware for my homebrew 3D printer so the default Creality configured Marlin firmware for Ender series is useless for me.