The details will vary depending on what device you use, but here is the overview:
Set your device to join the network MDS-public
In the Login screen that appears, click “Create Account“
Fill in the information, and then you’ll be allowed on the network. It’s a temporary account that will expire after some time.
If you don’t see the login screen after connecting:
Try to get on the web. Your browser should automatically go to the account screen.
Windows 7 [and maybe others] has a little dialog box that pops up after you try to connect, down on the bottom right, that says something like “more info may be needed – click here“. So click there, your default web browser will pop up, and you’ll be taken to the login screen.