AutoEnrol

When added to a course this enrolment plugin can enrol users onto a course automatically, either as they log in to your Moodle site or as they access to the course.
It was at first intended for use on site-wide courses such as "Moodle Help" or "Learner Voice".
In addition the plugin has advanced functionality to support automatically grouping and filtering users based upon their profile fields. Depending on how your user accounts are setup this may help you to give access to certain user groups.

Configuration of the plugin is managed by two capabilities which allow administrators to easily control who has access to the plugin.

Autoenrol filter use moodle standard availability interface that adds great flexibility in user filtering.
You can filter access to your courses using core availability plugins like date, user profile and sets of them or use additional availability plugins like: badge, other course completion, payments, etc...
The only limit is that the availability plugin rule should evaluate elements available outside courses.

The Moodle availability plugin for user profile fields unfortunately does not include language and authentication. 
If you need them, you can install additional availability plugins like Restriction by language and Restriction by authentication.