Professor McLaren was appointed to investigate the Rio 2016 allegations in June as part of the AIBA's steps - under new president Umar Kremlev - to reform the sport.
After an investigation by the International Olympic Committee, the IOC suspended the AIBA in 2017, banning it from organising the Tokyo 2020 boxing competition.
Professor McLaren - who investigated state-sponsored doping in Russia - found the manipulation structure within the AIBA was made possible because key personnel decided the rules did not apply to them.
He said the AIBA's then-president Wu Ching-kuo "bears ultimate responsibility for the failures of officiating at Rio and the qualifying events", and that Wu was supported by his executive director Karim Bouzidi in Rio.
"The executive director seized powers belonging to the permanent commissions. The commissions would let this happen as did the president," said McLaren.
"Once having acquired the power, he would oversee the appointment of referees and judges (R&Js) that knew what was going on but would comply with the manipulation or who were incompetent but wanted to continue as an R&J so were willing to comply or turn a blind eye to what was going on."
Wu was handed a lifetime ban by the AIBA in 2018.
"Boxing has a problem, it's not about the rules and processes. It's a people problem. For too long people have worked outside the rules," said McLaren.
In a short period of time, the AIBA changed its R&J system from judges being nominated by their own international federations, to an accredited 1-3 star system with the later addition of seven independently contracted 5-star permanent R&Js.
This led to "poorly trained" R&Js being "preyed upon by those who had corrupt motives".
In Rio, the executive director selected all of the R&Js. Corrupt members of the draw commission would influence the selection process, "so that the 'right' R&Js were in a position to officiate the bout as directed".
In a statement, president Kremlev said: "I am determined to ensure that boxers receive a fair fight. This determination is demonstrated by AIBA's clear commitment to uncovering the truth and acting on it.
"We must now carefully examine the report and see what steps are needed to ensure justice. What is important is that we make sure the mechanisms are in place to show that results are above suspicion."
Further reports on the investigation will be provided in November and then March 2022.
"AIBA hired Professor McLaren because we have nothing to hide," added president Kremlev. "We will work to incorporate any helpful recommendations that are made. We will also take legal advice with regard to what action is possible against those found to have participated in any manipulation.
"There should be no place in the AIBA family for anyone who has fixed a fight."
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