Task: Herbal Entrepreneurs doesn't let me take a plant sample

Unfortunately support for this game ended years ago, so this will never be fixed officially.

I'm the author of the mod that fixes the quest. The interaction prompt on the plants that is supposed to start this part of the quest isn't set up correctly, so there is no point in wasting your time trying different orders to approach this quest chain or whatever else people may suggest either.

It is impossible to complete (or even start) "Task: Running a Fever" without mods.