In this context it means exactly what you think it means:
very impressed by a famous people
Note that you don't need to meet a famous person to be starstruck. You can for example be starstruck in the presence of Jimmy Hendrix's guitar. Objects that are intimately related to a famous person can be awe inspiring especially if the object in question is one of the reasons that person is famous.
An architect or an architecture student will usually know who designed the famous building. In some cases, the architect who designed the building may be a "superstar" among architects. So it's not unusual to become starstruck by the famous person who designed the building when one is surrounded by said building.