There were additional files she was interested in leaking that she did not have access to.
She then obtained the password hash of an account that did have access and tried to crack the password, but was unsuccessful. She then sent the hash to wikileaks, not something wikileaks asked for, along with a request for help. There was no response.
Later she was in a chat with someone using a known wikileaks chat account. The identity of this person has not been established. She asked if they had been able to crack the password hash and that person said no they had not cracked it. They did not say they tried to crack it or they approved of cracking it. They answered the question factually, no, they had not cracked it.
Manning never hacked the system, but did try to. There's no evidence Assange attempted to hack the system. There's pretty solid evidence someone at wikileaks told Manning that they had not cracked the hash she had sent them, but none that they had attempted to do so. As far as the leaks that were published, none of these involved hacking, they were obtained using Manning's granted access. They were however unauthorized exfiltration of state secrets documenting war crimes.
This is the case alleging he actively assisted a leaker in hacking crimes.
This is where this breaks down. The account in question was a generic local Windows admin account, and she already had the same level of access as the desired account. It was only attempted to hide her identity.
This is clearly laid out as what happened in Assange's indictment.
This makes no difference, legally speaking. Assange was still helping her to gain unauthorized access to a computer system.
This is like giving bank robbers ski masks in full knowledge that they're going to use the ski masks to hide their identities during a robbery. You're still an accessory. It's no defense to say "Oh, I wasn't helping them to gain access to the vault, I was just helping them to hide their identities".