Naruto couldn’t perform the clone technique because he is terrible at genjutsu. The reason he could perform the Shadow Clone jutsu is it isn’t based in the genjutsu category, the clones aren’t illusions and are a direct splitting of his chakra as opposed to finely controlling used chakra to make illusory clones.
Normal clones are simply illusions, they can’t attack and can’t be attacked. Shadow Clones are not illusions, can attack and can be attacked. The Shadow Clone Jutsu creates copies of the user, however, these clones are corporeal instead of illusions.