I cannot tell from your question whether you are using an internal directory with LDAP authentication or an LDAP Connector.
There is also a choice to use internal groups versus LDAP groups. If you are using groups defined in LDAP then you can add the user to the group in the LDAP directory, rather than in Confluence, and Confluence can synchronize the group membership. If your user directory is "read only with local groups" then you can add the LDAP user to a group defined in Confluence.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.