You can log in to an existing Shared network if you know the log in credentials.  Select Log in to network from the Change network screen and enter the email address and password associated with the network.

The system has a security feature that limits the amount of incorrect login attempts and will prevent further log in attempts for a period if the attempts limit is exceeded.

If you cannot remember your password, then select the Forgot password option after attempting to log in (see Resetting a network password section)