Learn English – Expression for “be humble”

In common usage, infrastructure often is used unqualified to refer to good physical conditions in a community (as, for example, "Our town has the infrastructure to support your robot factory!"), although it implies little or nothing about tax, economic, and labor conditions. Of course one can also say "Their infrastructure is awful!"; that is, "good" is not an inherent quality of infrastructure.

Note, infrastructure is "The basic facilities, services and installations needed for the functioning of a community or society."

Regarding linguee.com, their "About" page clearly says, "there is no other technology anywhere else in the world that compares with Linguee", so obviously you should keep using it. :) They also assert that the translations they provide (which, if I understand correctly, are in this case English to German) are human-made (or at least human-moderated). In comparing the English and German, it seems that the connotation you suggested for the German word (i.e. "conditions necessary for a business idea to work out") do not hold up in these translations; for example, "worst imaginable conditions" going to "denkbar schlechten Rahmenbedingungen".

In A Dictionary of Hiberno-English: The Irish Use of English by Terence Patrick Dolan there is the entry: arm. Here we can read: "He came home with one arm as long as the other (i.e., without any kind of present ...)".

Also, on urbandictionary.com we can read:

One arm as long as the other
Basically turning up somewhere with nothing to give when something is expected. i.e coming to a party empty handed. Irish in origin

Jim: "Dave arrived in late to the wedding yesterday, the clown"
John: "Typical. Did he bring a pressie"
Jim: "Not at all, arrived in with one arm as long as the other [emphasis added]"

So, Spanish expression "llegar con las manos colgando" seems perfectly equivalent to English "one arm as long as the other".