D&D indexes are historically the worst. They spend more ink telling you where in the index to look next than had they just given you the pg # you were looking for.
So basically it's not an actual digital release. It's a limited online release for Beyond players only.
That's unfortunate. I prefer pdfs be made available.
I've run CoC at game cons for Chaosium many times. I've also run Escape on Mosek Uhn at game cons for Frostebyte Books. If you understand CoC's system you can pick up M-Space easy.