The AN01 adapter is used to mount the hole saws from 9/16" to 1-3/16" in diameter to the mandrel.
The AN02 adapter is used to mount the hole saws from 1-1/4" to 6" in diameter to the mandrel.
I think you will need one of them. Which one depends on the size of the hole you want to drill.
Edit: Amazon does not have the AN01 one.