Everywhere I go I find a poet has been there before me.
But Freud is not on record has having said or written this.
It is likely a variation of another possible misquote: ‘The poets and philosophers before me discovered the unconscious. What I discovered was the scientific method by which the unconscious can be studied.’ Sadly, there is no direct source for this quote either. It first appears in a 1940 journal article by Philip R. Lehrman.
However, it doesn’t seem implausible that Freud would have said this, based on what we know about his love of literature.
https://www.reddit.com/r/psychoanalysis/comments/mtznyj/did_freud_really_say/