If you think you are not understanding, then don't be afraid to ask in the forum - many people have posts along the line of "I finished but don't understand why it works..."
As to understanding better, I would suggest copying the code into codepen and messing with it. Try to break it. Put console.log statements in there so you can see exactly what is happening each step of the way.
Algorithms are a different way of thinking. To some it comes naturally, others have to work for it. But I think everyone can get it if they work at it. (And that may just mean that some other part of the job will come easier for you.) And each algorithm you learn gets your brain a little more aligned to that way of thinking.
Also, if you search on the web (and especially youtube) you might find someone explaining it.
Is there a particular challenge that is problematic? Start a new thread in the forum and see if we can sort it out. I'm sure your not the only one.