Digidesign's AIR (Advanced Instrument Research) Frequency Shifter is a simple pitch shifting plug-in that comes free with Pro Tools 8. It can't be purchased outside of a Pro Tools 8 upgrade or purchase, so if you've got Pro Tools 8, it should already be installed. You don't have to do anything further in terms of installation, as it is all taken care of during the Pro Tools 8 installation process. The interface is also very simple to decipher, as it has a limited amount of parameters to use, and in general is pretty limited in what you can actually do with it. It simply has parameters for frequency, shifter mode and feedback, and mix. I don't think that you need a manual for it whatsoever, and I really don't think that they make manuals for these free AIR plug-ins anyway.
No one should be having problems running the Digidesign AIR Frequency Shifter. These AIR plug-ins are designed to take up less processing power, and the Frequency Shifter is one of the least taxing of the bunch. I just upgraded to Pro Tools 8 from 7.4, and I'm currently running it on a Mac Book Pro that has as 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I run Pro Tools primarily with a Digi 002R or a Micro Box if I'm on the go. I've never had a problem running the AIR Frequency Shifter, and can't imagine anyone having problems, but it solely depends on the system you're running it on.
Since the Digidesign AIR Frequency Shifter plug-in is free, it doesn't really offer up too much to work with. While the sound quality is clean and the interface is user friendly, there is really only so much that you can do with it. I can't really complain too much as the plug-in is free with Pro Tools 8, so behind paying for the upgrade, I didn't pay a dime for the individual plug-in. For doing basic pitch and frequency shifting, this plug-in will do the job fine, but just don't expect too much from it. I would however encourage all Pro Tools 8 users to check out the AIR Frequency Shifter as well as the other free plug-ins that are new to Pro Tools 8, as they are a great addition to the software.