Cancellation of the installation appointment at Allkauf Haus - costs or compensation?

In the highlighted text it says that permits for utility connections and traffic areas must be obtained. A property from one neighbor or another is not a traffic area.

The text I highlighted refers to utility connections and traffic routes. Correct. The entire sheet is full of your tasks.
I read it again and know what you mean: you have tasks, but it is not necessarily explicitly stated in some points that it must be in writing. For that, you probably have to know contract law again.
how was it “packaged” with you?

General wording in a contract and terms such as "all," "entire," "important," "necessary," etc. must be formulated precisely. One cannot expect another person to take care of something they are not aware of. Requirements must be clear and unambiguous. When defining the requirements for traffic areas, utility connections, crane sites, access options, pipelines, and other things, one could have also mentioned approval in such cases. Tomorrow I am meeting with a lawyer and will let you know what he says about it.

Ever talked to the neighbor?

He is still on vacation all next week…

I cannot understand how anyone could come up with the idea of defending the construction company. They must have checklists for every project because besides things that the client has to provide, there are certainly plenty of things that need to be clarified internally. And now someone seriously believes that the list is checked only a day before and then the appointment is simply canceled because the necessary permit is missing? Normal behavior would be to contact the client (first by phone, if unreachable then by email). If an appointment falls through at such short notice, internal rescheduling must take place as well. Or do they just spontaneously set up another house somewhere? Hardly.

It was simply poorly organized, there is nothing to discuss. Probably something else was missing and that was just a pretext.

If I were to postpone the start of a project by several weeks at work because I was missing feedback from the client on an issue and didn’t follow up when I noticed this, there would definitely be serious trouble. Not to mention that I would never even think of such an idea.

They must have checklists for every project, because besides things that the client has to provide, there are certainly plenty of things that need to be clarified internally. And now does anyone seriously believe that they look at the list one day before and then simply cancel the appointment because the corresponding approval is missing?

Yes, I think the site manager wouldn’t have been scared, but the vacation substitute probably was.

It was just poorly organized, there is nothing to discuss about that. Probably something else was missing and that was just a pretext.

Yes, presumably a capacity problem was poorly solved elsewhere. That the train driver should first get a warning tone before the whole train emergency brakes, I agree with you. The sudden cancellation was not appropriate, I agree with you on that. That is probably the classic: someone is supposed to appoint a vacation substitute - but whether that person is already ready for vacation themselves is not checked; and they are also not relieved from their regular work to an appropriate extent. Vacation "planning" without substitutes is unfortunately common in many companies.

how was it "packed" with you guys?

Please excuse me, but I don’t understand what you mean. Could you please explain it briefly?