I was cut off by their hiring manager (P) 10min into the call. Literally the worst interview experience I've had. She was rude and not professional at all. Imagine all the preparations I had! Ugh!

Not too hard. It doesn't focus much on related financial knowledge, but instead, understanding on the position. The process is more about knowing u in person, and what's ur thoughts and expectations. It also includes section where they told u what they expect and give u details on ur scope of work. After all, just prepare a bit on basic finance knowledge and be confident should be fine. This is a good company, and keep in touch with the career website.