An does not exist as a direct, automated tool because the two file formats are fundamentally different. MP3 is a finished audio format, while FLP is a project file for Image-Line's FL Studio.
Forget the fake converters. Here is the real 10-minute guide to building an FLP from a downloaded MP3 using free online tools + FL Studio. mp3 to flp converter online
This article explains why a direct conversion is impossible and provides the exact steps to achieve your goal manually. Why Direct MP3 to FLP Online Conversion is Impossible An does not exist as a direct, automated