Duties of a carport manufacturer

Wrong. For the installation, construction, etc., there is a separate site manager who must be appointed.

Ok, and does he do it for free?

That is actually standard. Architectural services need to be paid for, and not a little.

I'm surprised now though, I thought a signature costs nothing

That surprises me now, I thought a signature costs nothing

Guys - don’t play dumb on purpose now.
Of course, the architect’s service costs something. But with prefabricated houses/buildings, it’s always mixed calculations.
For example, I bought a house from Heinz von Heiden and paid an amount X for it. The architect’s service is naturally included in that, and no one demands additional money for it afterward.
And it’s no different with them. Or do smaller carports that don’t require approval get a surcharge just because they could be built without a signature and thus no money comes at this point?
And whether the construction manager gets money is irrelevant here.
He has completely different tasks, and that’s not what this is about at all.

Right, but then it is also shown in an invoice beforehand.

No, not always. But you are free to have everything billed according to HOAI by the carport company if you wish. Then you will receive all the documents you want.

Guys - don’t play dumb on purpose now. Of course, the architect’s service costs something. But with prefabricated houses/buildings, these are always mixed calculations. For example, I bought a house from Heinz von Heiden and paid a sum X for it. Of course, the architect’s service is included in that and no one demands money for it afterwards. And it’s no different with them. Or do smaller carports that don’t require approval get a surcharge because they could be built without a signature and thus no money comes in at that point? And whether the site manager gets paid is irrelevant here. He has completely different tasks and that’s not what this is about.

You don’t understand the core problem. Requirements vary nationwide for outbuildings depending on the authority. Mostly, carports are exempt from approval. You found a cheap carport manufacturer, but obviously not well informed and are trying to shift the costs onto him. A building application costs between 500-2000€. But I’m not surprised. Anyone building with Heinz von Heiden tries to turn every cent over. Services cost money after all!

And what you also forget! If the building application is incomplete, there are problems or questions. Who clarifies it? You or the carport manufacturer?!