Piply is open to anyone who can reach it until the first account exists. Creating one turns sign-in on for everybody, so do this before putting Piply on a network other people share.
This account can do everything, including creating the rest. You will be signed in as it straight away — there is no separate sign-in step.
Skipping leaves Piply open with no sign-in, which is fine on a laptop. You can create the first account later under Settings, or with piply users create <name> --role admin.