This conversion guide is now somewhat dated. The guide was released in 2007 (11 years ago as I write this). That's right about when Evil Hat started using Fate (the word) instead of FATE (the acronym). More to the point, it's 6 years before Fate Core and Fate Accelerated were released, and it's when d20 3.5 was the latest d20 release.
The guide is most useful if you're converting from d20 Modern to Spirit of the Century. It has you create up to 10 aspects, just as you'd get for a player character in SotC. It maps d20 Modern skills to SotC skills.
If you're not specifically converting from d20 Modern to SotC, this guide won't do much for you. You'll have to come up with your own skill mappings. The Fate "aspect economy" in Core and Accelerated would have you create no more than 5 aspects instead of 10. You'd come up with your own conversions for creating stress tracks. You could still use the guide's conversions from d20 ability modifiers to levels on the Fate ladder. The guide already suggests that you create Fate stunts from scratch instead of trying to convert anything to stunts, so that guidance can still be applied to newer editions of Fate.