driving 8x8 LED using 2 74HC595

... make sure that 2803 is the one that you put only one zero on at a time and put the data for that row on the top 595.

What do mean by that? Do mean that 1 led can only be turned on at a time?

Or do you mean that each pin on the 595 can only handle 20mA on each pin, and that I can only turn on 1 darlington pair at a time?