>“knowingly and unlawfully conspired with Chelsea Manning to commit the following offenses against the United States…”.
Why are you quoting that part rather than any of the actual offenses? He undoubtedly conspired with Manning to receive classified documents for the purpose of publishing them, which is what the plea details.
Part (a) even says he "received or obtained" classified documents from a person knowing that they were illegally obtained. It doesn't say he helped with the illegal obtaining.