The QR code taped to the wall is the usual answer for guest WiFi. It works well on phones, but not on laptops.
A laptop does not have a camera pointed at the wall. Some have the camera covered with a sticker, others have no app that reads a QR code at all. The people who need the network to present something end up asking for the password.
What we do instead
Ripple broadcasts its own open network. When someone connects to it, their operating system checks by itself whether there is internet. There is none, so it automatically opens a page, the same way hotels and airports to show you their login form. That page shows your real network name and password, with a button that copies it.
Every operating system checks differently: Android asks one address, iOS another, Windows and macOS each have their own test addresses. The board handles all of them separately, as each one expects, otherwise the page would open by itself only on some phones.
What it cannot do
A web page cannot tell a laptop's WiFi adapter to join another network. That is an operating system security restriction, not a limitation of the device. So the guest still picks the network from their own settings, but the password is already copied.
For the same reason, Windows and macOS usually show a "Sign in to network" notification that the user taps once. It cannot be bypassed from software, so we do not pretend it is not there.