If your property is a type that can get a score as a campus (Hotel, Multifamily, Senior Care, Hospital, K-12), then the answer is: No, you don't have to create individual buildings. However, if the buildings are individually metered, the best practice is to benchmark them individually.
If your property is NOT a type that can get a score as a campus (Hotel, Multifamily, Senior Care Center, Hospital, K-12), then only your individual buildings will be eligible for the ENERGY STAR Score, so you should enter them individually. If you can't because your buildings are not separately metered, then you can benchmark your buildings together, but you are not eligible for certification.
See our "How to Benchmark A Campus" guide for more information.