White People Can't Like Black People?

I can only assume this person is angry and hurt from the decades of oppression but an African American woman said that I cannot be part of my school's BLM club because I'm white. I realize the systematic oppression and privilege I get from society unconsciously but I always have seen my black community and black people as my equals. I feel like police brutality to them is horrid that's why I jumped in a fight myself (my best friend Tee Tee was about to be slapped, long story).
Am I wrong or was this just an example of how the world has become so divided by things as superficial as race, religion, and political agendas? Things that should not matter, but sadly, because of society... do matter... It hurts that I cannot do more. What can I do even more to aid my community? Black or white, Hispanic or Japanese, everyone matters. It just so happens that society treats blacks horrible. It has to stop— through example. What can I do?
Anon for the racist pricks out there