Install the software. During installation, decline any bundled software offers (usually none from the official source).
While the desire to save $50 is understandable, the search for a free code is a minefield. You are statistically more likely to infect your computer with a virus or steal your own data than you are to find a working code. Even if you find one, it will likely be deactivated within a week.
: Usually discounted to around $44.76 (from $55.95) for 1 PC and up to 6 devices, including lifetime updates.