I am kind of a new player even if I played multiple other simulations, but I struggle to be on time especially with the "Turn Around at Aachen", just at the first station I am already lasted and i am always at full legal speed and i don't understand why i am never on time with this scenario so if you could help me i would be grateful because for now I don't really like this game since I am always late.
Try a timetable service since some scenarios have impossible times. Generally being late is not much of a issue as you can stil get gold even if you have some delay. And even if you don't get gold it doesn't matter much if you had a good drive. You also need to find a balance between acceleration and brake points, for regio services particularly you need to accelerate quite fast and also start braking closer to station's in order to keep time. And don't go to extremes like 100% throttle from stand still or emergency brake close to station but find the sweet spot!
I would say it's not possible to be on time for all the stations on that specific scenario. Since it's raining you'll easily get wheelslip, especially when braking. Anyway, as dbrunner#4864 said, who cares about the timetable? Sure, try to keep on time, but in the real world safety comes first (and also a bit of comfort for the passengers is not wrong either ).
two things that you can do in order to improve your timing: -you can learn how long the doors need to be closed and time it with the loading passengers instruction, so that your doors will close shortly after the circle is full, instead of closing the doors after the loading circle is full. -on some services you will have the "wait until" prompt (mostly at the start of a service or sometimes when you are really quick). You do not have to wait and can actually already start your train to make up for some time. This would not fare well with passengers in real life, but in this game no one cares