You receive a business login (email and password) and a store ID. Sign in at /login.
Click Connect Square, sign in with the Square account that runs your register, and approve read-only access to orders. Nothing is installed on the register and your printers keep working.
Under Kitchen PIN, choose 4 to 8 digits. Tablets use the store ID plus this PIN to sign in.
On each tablet open /kds, enter the store ID and PIN, and pick a station or All items. The choice is remembered on the device.
Ring a small order on the register. It appears on the screen within seconds with its order type, items, modifiers, and notes.