Users can either be set up manually within Butler and use the built in authentication. It is also possible to connect Butler to LDAP to use LDAP for authentication.
When Butler is configured for LDAP, the user will be automatically created on first login. Whether the LDAP authenticated user will have access to different areas of the Butler depends on if they are connected to an LDAP group that has access. If not, they will just be able to login, but not do anything.