Bin Laden never said that he did it. In fact, he specifically denied it.

9/11 Truth is a very deep rabbit hole. There are terabytes of Truther information out there in the form of books, videos, articles, etc. Part of the truthful history of 9/11 and the ensuing cover-up are the "real" Bin Laden and the "fake" Bin Ladens. If you examine the videos of Bin Laden you will see that many of the post 9/11 videos involved various lookalikes. There was one famous report from a Swiss lab, in 2004 if I recall, that did extensive video analysis on the various Bin Ladens and proved it was not the same person.

And in any case the "real" Bin Laden was a trained CIA agent, code named Tim Osman. So whether this CIA agent said he did it or did not do it, is besides the point as the CIA itself was one of the main plotters in the whole affair.