Securing a open Wi-Fi network

New place, new environment.

We will need to secure the open Wi-Fi network in a school district, what we are trying to accomplish is that anyone that logs in to the open Wi-Fi will have limited access and restrict them to not do damage to our network and other unnecessary things. Best case scenario is to have authorized user’s access resources like files and folders etc. within the domain. Our environment briefly consists of Cisco wireless controllers, no radius server and windows server. Any solutions to secure open SSID - create a new one? Or modify the existing one. Any suggestions and guidance with our existing infrastructure will be great.

I heard of many solutions, one example was to have a separate ISP for the open Wi-Fi users, more cost :( or have every user login and authenticate, so they can have certain resources (Files/Folders) but that seems to me that we need more stuff involved?

Any other info I’m missing please let me know.