If you are a legitimate FL Studio owner (you have a registered account with Image-Line), follow these steps:
Today, Image-Line provides a fully native macOS version (starting from FL Studio 20), which is highly optimized for and modern macOS versions like Catalina or later. While some producers still seek out FL Studio 11 for its specific aesthetic or the "nostalgia" of its step sequencer, version 11.0.3 remains a relic of the software's transitional phase before it achieved true native status on Mac. FL Studio 11.0.3 - 64 Bit Beta FL Studio 11.0.3 Mac OS X.dmg
If you want, I can list differences between FL Studio 11 and the latest FL Studio for macOS, or provide installation steps for a specific macOS version. If you are a legitimate FL Studio owner