Is croup contagious to adults? My niece has it she lives upstairs and she hugged me hours before she got a fever. Am I at risk

Yes and no. Croup is triggered by several common respiratory viruses that can infect anyone at any age that is not immune.However, the response of each patient is different.Croup is a pattern that involves the rubbery and small airways of kids & primarily emerges in those 6m to 6yr. Older kids and adults tend to have a cold/cough or laryngitis with the same germ.If you had that strain as a kid you are immune.
It is unlikely. For an adult to get the croup. Croup is caused by a virus which inflames the larynx (voice box). In children the larynx is small and when inflamed it makes it hard for the child to breathe. It is unlikely it will cause similar difficulties in an adult as the larynx is much wider in adults. The worst case scenario and adult will develop laryngitis and lose his/her voice for decades days.