can people play music for crowds in the mall?

Yes, you can play music depending on the type, nose level, instruments, and size and length.

You would need to ask the management first. As long as you are not asking for donations or soliciting for something, I don't know why they would turn down a free concert.

I've never seen it done in Tacoma Mall or outside of it. Your call to try. They have security rolling around on wheel machines just a heads up