This sounds like the monopoly on busking that Manitas referred to earlier in this thread.
We do not not know yet if this is a by law or whatever or how it is to be enforced (if indeed it will, or is) or if it can but:

Is it a measure designed to ensure that the maximum revenue is gained from busking for the festival funds?

Or one to discourage busking generally?

Or an outdated, badly thought out and judgemental half-measure, that will achieve neither of these ends but just confuse the issue even more?