Financial analyst interviews ask whether you can explain a number, the assumption under it, and what would make the number move. A model nobody can follow is not a skill. A clear bridge from last period to this one, with the driver you trust and the driver you do not, is the skill.
Keep two pieces of work: a forecast or a variance you presented, and a model or a memo where someone challenged an assumption. Know which inputs were yours, which came from a partner, and what you would not stand behind. If the work was a class case, say that before you describe the file.
Practice without a spreadsheet in your lap. If you cannot say the story of the change in sentences, you will freeze when they take the screen away.