Translation:Group work is hard for all members of the group.
I was curious about this, so I looked up both bab.la and Cambridge English-Danish dictionary. Hårdt is used for the abstract version of hard as well: https://dictionary.cambridge.org/dictionary/english-danish/hard
Group work has a different meaning to teamwork. It usually refers to a classroom setting (whether at school or a training session in a business environment), with a finite timeline and task - usually an exercise to be completed, often with a presentation or report at the end.
Teamwork tends to either refer to an ongoing project (a sports team, or maybe a sub-department in a business) with targets to be achieved repeatedly (winning matches, reaching sales targets each month, etc.), or to people spontaneously working together to overcome something (often unforeseen).