In the Space settings of one of our customers' Space we add users at 'People': 
In this exact space we create sprint tickets. When we share the Space environment or/and specific ticket, with the recently added user, he is not able to get into the space nor the ticket. He will be led to a different area in Jira.
My main question is: Do I have to add this person anywhere else, than the space? How is it possible that he is still not able to get into our sprint Space?