I didn't figure it out on my own. I googled it and there was a tutorial. I was much too much of a novice back then to decode it on my own.
It was so different from other tesses that I'd done up to that point in the past.
I can't find that tutorial anymore, but I still remember the basic techniques. I use them sometimes to recreate the works of others and to come up with my own designs.
Now that way of folding is one of my favorite methods, even though it can be quite difficult and fussy.
The inner corners of my rhombuses are a little bent. The folds are so small and delicate. Bigger and/or sturdier paper would be required to really get those points to pop. But I am still pleased with the end result.
The crease pattern is pretty straight forward.
I also really like the back side shown below. It's a great pattern in its own right.