In tasawwuf some times people do have spiritual experiences which are not because of Jinns or Satan. For example, Hazarat Jalal ud Din Sayuti saw Nabi (PBUH) 72 times while awake.
Answer
I believe that Satan has a trap for everyone. If his trap can fool people into believing that certain ordinary mortals were extraordinary people who should be respected and adored in an exaggerated way to the extent that they are worshiped, why should he not set the trap?
For someone who was not a companion of the prophet, alaihissalaam, dreaming of him, whether while asleep or awake, may not necessarily mean that he actually saw him. Only the companions knew how the prophet looked like. According to a hadith, Satan cannot appear like the prophet in a dream. However, that statement does not preclude that possibility that he can come in someone else’s appearance to fool a Muslim that he was the prophet, alaihissalaam. I am therefore not very sure whether Shaikh Jalaluddin Sayuti saw the prophet in his dreams or not.