There are peaceful/permitted protests that the police leave alone and occasionally support/join.
There are peaceful/not-permitted protests that the police disperse with various uses of non-lethal force.
There are Rioters that vandalize and try to blend with protesters but seldom directly confront the police - occasionally confronted by protesters.
...and then there's just tons of rampant looting with little police intervention.
Anyone blending these four distinct phenomenon is just doing truth and justice a disservice.
The other option, more literal, is "they got a permit to do this protest", but there have certainly been plenty of peaceful grassroots protests that got no sort of official go-ahead and yet were executed perfectly fine on both sides.