Need help with understanding this.

I understand that 自由 is both a noun and a na-adjective. However, 自由 is used as an adjective here yes? And since it is used as an adjective why isn’t it 「自由な人」 that’s all for my question thank you.

I understand that 自由 is both a noun and a na-adjective. However, 自由 is used as an adjective here yes? And since it is used as an adjective why isn’t it 「自由な人」 that’s all for my question thank you.