I started to learn R at the HarvardX data science series at edX.
Here is the list of the courses
Each course provides the direct interaction in DataCamp.
I took the course as an audit member, which is free.
But, DataCamp gave me the certificate of the course accomplishment when I finished the drills of the course.
I finished the course 1, 2, 3, and 5. I will follow up the rest of the courses.
This is the extra document of Rafa's course : rafalab.github.io/dsbook/