That open plaza area is the same as an enclosed mall as far as ownership goes. The land is owned by a company that leases the retail space. There is an onsite management company. These are probably the people who decided that you were using their property for your apparently commercial purposes without paying a fee.
If I carry one of my cameras into my local mall, I often get stopped and asked what is my purpose for doing so, even when it's Christmas time and I'm taking the grandkids to see Santa. Thirty people can be shooting a NASCAR driver at a mall event with their little point and shoots and I'll be asked what I plan to do with my pictures. Even though I'm retired, I've taken to carrying my NPPA photo ID with me so I can claim press privileges.
