Hello Steve Kim,
The advanced version of Easy Populate (EPA) is a commercial version and supported by the retailer, or the publisher. The instructions you quoted are for the basic Easy Populate, version 1.2.5.4, not the newer (and more buggy) version 2.7x.

Please keep in mind that these are generic instructions, that will work on the majority of systems. Unforutenitly, not all systems are set up the same. Some people may still be running version 1.28 of Zen Cart, while most of upgraded to version 1.37. Some hosting companies may still be running Apache 1.x/PHP 3.x, while most have made the switch to 2.2x/4.x. So, while the instructions are fine in a general sort of way, your mileage may very.

That doesn't mean we wont help, just that we will have to figure out what is happening. I am not the one with knowlge in this area, so I will leave the rest to someone else.