Acrylic cutting advice

That’s probably because there is no direct link between the two. Conveniently I commented on this earlier today here, let me know if that clears things up a bit?

Chipload = feedrate / (RPM x nb of flutes)

and that’s about it. DOC you set almost independently

Chipload guidelines are like religions, there are many and you can pick one, or none.
The chipload guideline I mentioned in the ebook is derived from this loooooooong thread, it is crowdsourced if you will, and then I tried to back it with my own experimentation.