Does anyone have experience with German research statements?

I'm applying to a German postdoc, and it requires a motivation letter, a research statement, and a CV. So far, so good.

However, I've never written a research statement and I'm getting a bit confused about what goes into the research statement and what goes into the motivation letter or CV. A lot of online guides as to how a research statement should be structured say that it should begin with introducing yourself and your previous research experience, i.e what you've done and what your role was, and that it also should include a motivation for why exactly you want that project, etc.

My thinking is that surely, I would already introduce myself briefly in the motivation letter, and the motivation letter would also state why exactly I want this job. And specific former projects, conferences, positions, etc. would be in the CV. So this seems like repetition to me.

So how much should the research statement just focus on experiments/methodology/fit, and how much should I summarize up the CV and motivation letter again?

(Also, any other general tips are of course welcome.)