Originally Posted by R.Petrov
My phone is completely stock and I still can't download this update. Maybe because I live in Europe... This is awful.
you said, you've got TWRP recovery installed, so your phone's bootloader is definitely unlocked and you've got a custom recovery installed. The update only works if /system partition is completely stock, you've got stock recovery and your bootloader is (re-)locked.
if anything doesn't match your phones CID, the update won't install.