Generating Radius users on the fly

I’d like to setup a guest WiFi network which generates users/passwords on the fly as each one is used, the next becomes available.

So... a guest comes in, they enter in the details (scan a QR code) and join the WiFi with a 1-day voucher. The next user/password is generated and ready for use.

I am using JumpCloud right now but am in the process of trying out Windows Server.