If you are looking for Filmora 8.3.5 specifically because your computer is older, or you just want a simple editor, here are the safest ways to proceed:
Wondershare has transitioned away from the old "Licensed Email and Registration Code" system to a modern account system. Because of this: Filmora 8.3.5 registration code
Modern versions of Filmora (like Filmora 13 or 14) are much better optimized and offer a "Free Tier" that allows you to test all features. While the free version has a watermark, the subscription or perpetual license is the only way to get a guaranteed, working activation. If you are looking for Filmora 8