Ready to move on? Cool!
Usually people can shred on thin strings but when they hit the low and thick strings they get into trouble as these strings behave a bit different and require different strength applied to function properly. That's why this exercise should be really useful.
It's hard to make these things work smoothly and fluid so don't worry about your speed - the quality is what you need. Set a very low tempo and make each note stand out to feel the strength needed to make the string sound good.
Now we'll move to the next lesson and work on similar exercise using thick strings only.