Congratulations!
The second stage is the final one and I did it online too! It consists of two interviews. The first one is based on your CV, your experiences and your motivations. The second interview is an article based interview and it is pretty straightforward. You then have a discussion with two partners about the article. I really enjoyed this process, it was really fun and engaging. I would not worry too much!
I prepared by discussing unseen article with friends two weeks before the interview and it worked out for me!
Good luck with the process!!