The controls match the OBS beauty filter. Those pages also describe selecting a source, signing in, hold-to-compare, and effect presets. None of that applies here. There is no Facebetter account. Purchase and the trial watermark are handled in FxFactory. See Install.
Final Cut Pro
Adjust effects
The seven pages on Facebetter Beauty in Final Cut Pro and Motion.
Apply Facebetter Beauty to a clip. Adjust it in the effect panel. The picture is processed on this Mac.
Each page has its own reset. Other pages stay as they are.

