Does it mean "is not successful in finding"? Wouldn't it be more common in English to say "can't find" in such case? Can it be translated that way? I got the impression that it possibly could be because the Norwegian verbs in present tense can often be translated into English in Present Continuous as well as in Present Simple, and when I try to understand this phrase "in Present Continuous" it sounds to me like "cannot find", i.e. "is trying to find but to no avail". For me the English phrase here sounds more like a part of a bigger "chain of events" in Present Simple. Is that so in Norwegian too?
You're right: the first two are equally acceptable English translations, and the Norwegian is the same in both cases. But you cannot translate this sentence as "cannot find" because the Norwegian is missing the modal verb å kunne. That sentence would be Ulven kan ikke finne elgen.