Hole for fan - What size?

I need to clarify something:

Luftbude has it right – they have realized that it makes sense to use 180mm. They also have their own installation teams who have probably already "tested" it.

However, the installation manual directly from the manufacturer Südwind states 160mm, which in my opinion is quite suboptimal.
ambientika.eu/c/gebrauchsanweisung/ --> scroll to Ambientica smart --> to the ventilation device manual --> p. 44, picture 1.

That's why there is always some confusion. I hope I was able to provide some clarification...

... for me it is page 49 ... but never mind. You are of course right that this is quite confusing. I am of the opinion that the main issue with the picture is the distances to the side wall and ceiling, but that is not helpful for the user.

Normally I also always recommend the manufacturers' websites ... but here it is really very vague.

Thank you very much for your effort, I have now had a craftsman do it on site. He charged 180. So you were basically all right.

The manufacturer's instructions really did say something about the 160mm. Pretty annoying. If I had done it myself, I probably would have been annoyed if the drilling had been 100% precise (which in my case would have been very likely).