GNU/Linux MX 19 Installing Broadcom BCM4331 Driver Guide
Hi! The linked Tutorial shows you Step-by-Step How to Install Broadcom BCM4331 Wi-fi/Bluetooth Driver in MX GNU/Linux 19.
The Package Provides the Source Code for the wl Kernel Modules and makes use of the DKMS Build Utility to Install them for the Running Kernel.
GNU/Linux MX Broadcom BCM4331 Driver Installation Guide
Broadcom BCM4331 Driver Installation in MX Linux 19 Guide