I'm not trying to automate logging into Designer Studio but use the inbuilt Pega Robotics utilities ("Enter RPA Credentials") and use the runtime-config.xml to register the robot with the Designer Studio (please let me know if my assumption of your response is incorrect).
I can login to the studio using the LDAP credentials for the robot, but if I try and use them for the API call under Resources --> Pega API (i.e. pega_url.com/PRWeb/api/v1/cases) or any variant of it that uses LDAP (i.e. a PUT command for pega_url.com/PRWeb/PRWebLDAP1/api/v1/cases) this fails.
I can use local designer studio authenticated robot users via this method but not LDAP robot users.