If your goal is just to place and protect an affiliate link on your FB profile, Linktree is usually enough and the cheapest option. It’s widely used, trusted by platforms, and doesn’t raise suspicion.
For extra security, you can use a custom domain with Linktree or similar tools (Beacons, Carrd). This helps avoid link blocks and looks more professional.
Just don’t use shady link shorteners, because Facebook may limit reach or flag the profile.