This plugin is based on the core enrolment cohort.
Within this plugin we add a course greeting to the plugin similar to the self enrol plugin.
For documentation of the core enrolment cohort functions look here: http://docs.moodle.org/en/Cohort_sync
There is although a tracker entry to improve the cohort core module with this function: https://tracker.moodle.org/browse/MDL-38695
To install elediacohortgreeting just copy the folder "elediacohortgreeting" into your moodle/enrol/elediacohortgreeting.
After that you have to go to http://your-moodle/admin (Site administration -> Notifications) to trigger the installation process.
The greeting text can be configured in each enrol instance of this plugin.
So you can have multiple instances with differnent greetings for differnent groups in each course.