Is there any document or sample example on how to use External Authentication. All users are stored in CSV and this CSV gets regularly updated. How can I authenticate users in Moodle using CSV. What fields should I entered inside Host, User Name, password. I tried various combinations but nothing works.
There is no authentication method that reads directly from a CSV file.
Your best plan is to write a script that regularly loads the CSV into a suitably formatted database and then uses external database enrolment. See External_database_authentication.