While you won't find a legitimate floating around the web, the 30-day "use" trial is the best way to get started. By the time the trial ends, you’ll know if the software is worth the investment—or you can use a 50% discount from NaNoWriMo to make it highly affordable.
Literature & Latte (the creators of Scrivener) uses an online activation system. Publicly shared keys are quickly blacklisted and will stop working, often right in the middle of a writing session.
The best way to "install Scrivener for free" is to use their incredibly generous official trial. Unlike most software that gives you 7 or 14 calendar days, Scrivener offers a
