Two points - 1) The OTO is the Outer Order. 2) After turning the OTO into his Thelemic propaganda machine, Crowley set up the A.:A:. because I believe he knew that OTO was an old aeon hierarchical conception and he was happy to have a propaganda machine promulgating his word. He knew he couldn't change it so he made it work as best he could to serve his purpose and then set up the A.:A:..
And so on. Just so you'll know, friend, Crowley didn't join the OTO until years after he created the A.'. A.'. And I am about as much a propagandist for the OTO as Michael Moore is a spokesman for K-Mart.