There seems to be some misunderstanding regarding plagiarism. In particular, whenever you use an online resource which you just copy, that is considered plagiarism (regardless of whether you provide the URL). All answers are supposed to be in your own words.
Moreover, if you have the same solution as someone other than your submission partner, this is also plagiarism. We have seen cases where two students had the same solution but different tutorials. It is not entirely hard for us to find such cases.
In particular, to be very clear: the first attempt at plagiarism gets you 0 points for that sheet, the second time we forward your information to the Prüfungsamt and you lose the right to take the exam.