I don't think nails are mentioned in the FAQs themselves, but you're perhaps referring to the "Beginners start here" guide, where there is the comment "Well shaped and smoothed nails are important for good tone" followed by some tips on achieving this. The important thing there is that if you do have nails, they should be properly shaped and smooth, or they will produce bad and scratchy tone. However, some people, from necessity or preference, do play without nails and, while it gives a different sound, there shouldn't be a problem with your doing that in the lessons.
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