New Grad Mistakes / Absent PM

I was hoping if someone could please give me some advice as I’m really stressed. 
 

I am a new grad and I have been at my job since September. I was involved in projects right when I got hired and then for a month I had an empty period (the project ended) so to “gain new skills” I reached out to different teams if they needed help on a project with smaller tasks. A team reached out to me, and I explicitly explained I don’t have experience in their department  but I took some classes on the topic in university so it would be fun to learn by helping them.

Well, turns out, the director I spoke to gave the project to someone else without telling me. And this guy never comes to the office and never schedules meetings with me. I met him once briefly.  He doesn’t even answer my messages all day and cold calls me in the evening. He just gives me various tasks whenever he feels like it. The last task he requested really went bad. He wanted me to do some data analysis with 30 csv sheets he dumped on me. And just under 10 min explained what he wanted and I took notes. He didn’t answer me the next day when I had questions and basically I did what I thought I understood. I asked him if he could review my work before sending the final version. This was Tuesday evening, he tells me, “yes this looks good. Go ahead and do the same for the rest”. I completed it by Wednesday and sent it to him. He calls me in the evening angry saying this isn’t at all what he asked me to do. He said not a single thing is correct and I misunderstood all of it. So I ask him, okay do you mind explaining what exactly you wanted because I clearly misunderstood. Can we go over it? And he tells me “this is super simple. I’ll just do it”. And kinda angrily hung up. I got super stressed. He told me one day this is good and the next day everything is bad?? I was so confused and felt so stupid.
 

The director that got me involved did say this would be a learning opportunity and more of a shadow work than actual involvement. I don’t expect to be held by the hand but this is outside my department and field and I am a new grad. I don’t have the same amount of knowledge and experience as the project manager who has a PhD in this fields Also, my actual team (the one I am hired with) started a project and i am juggling both projects. 
 

My manager told me she wants to have a discussion about my work load and especially about the other department’s work. Should I be honest with her and say while the topic is interesting, I don’t have enough skills to keep helping them? Will that look bad on my part? All the other reviews I had received before from my other projects/work were very good so I am kind of scared of messing up everything all of a sudden. Should I tell her about the situation where he said my work is satisfactory and the next day nothing is right? Will that department blacklist me in the future ? 

this is in infrafund idk if that’s relevant. Sorry for the wall of text. I’ve been panicking all night and have a meeting with my manager tomorrow