I've had years of experience as a PL/SQL developer and am familiar with packages, functions, loops, conditional statements, etc. That part of the course is easy for me. Where I'm struggling is in the programming assignments, which as others have said aren't well-related to the lectures (those are useful for overview/background). I've spent hours googling, watching other tutorials, etc., in order to figure out what R-steps I have to take in order to be able to get to the looping/conditional statements steps. I've paid for this class, but right now it looks as if I'll drop it, take the rest of the specialization for free (downloading absolutely everything as I go, including datasets), work through at my own pace, and officially re-enroll and complete it when I'm much more familiar with R. Then I won't be spending 15+ hours/week figuring out the basics.
One tip: purchase the author's book. It's quite helpful for the quizzes, though not so much for the assignments.