Original quote from US Bill of Rights: "Congress shall make no law ... abridging ... the right of the people peaceably to assemble..."
Individuals have the right to form groups and organizations of any kind, and hold meetings and other activities anywhere and at any time, as long as they don't violate NAP (as for example by trespassing, blocking traffic, causing a safety hazard or harmful pollution, or genuinely disturbing the peace). If there is no NAP violation, government must not interfere. Government is prohibited from restricting any protest, demonstration, meeting, or other assembly to a so-called "free speech zone", since the entire country is supposed to be a free speech zone.