To use, move the contents of the zip to the root of Payday 2's install directory (and replace anything if it asks, such as if you're updating the mod). Then choose which loader corresponds to what OS or distro you have, run the prereq-script that is associated with your OS so it'll install what's needed, then add this command to the launch options of Payday 2 on Steam:

env LD_PRELOAD="$LD_PRELOAD ./libsuperblt_loader.so" %command%

If you want to use MangoHUD, use this command (and yes, this was a PITA to figure out):
env LD_PRELOAD="$LD_PRELOAD ./usr/lib/mangohud/lib64/libMangoHud_dlsym.so:/home/[your_username_here]/Documents/payday2-superblt/build/libsuperblt_loader.so" mangohud --dlsym %command%

This'll tell the game to find the loader.

If you are experiencing crashes due to LLVM15, then run this command instead to use Zink, an OpenGL -> Vulkan conversion layer. Note that there may be some performance issues on certain heists (weird spiking in GG Casino's vault, but that's not exactly the poster child for PD2 heist performance anyway):

env __GLX_VENDOR_LIBRARY_NAME=mesa MESA_LOADER_DRIVER_OVERRIDE=zink GALLIUM_DRIVER=zink LD_PRELOAD="$LD_PRELOAD ./libsuperblt_loader.so" %command%

If you want to enable MangoHUD with Zink:

env mangohud __GLX_VENDOR_LIBRARY_NAME=mesa MESA_LOADER_DRIVER_OVERRIDE=zink GALLIUM_DRIVER=zink LD_PRELOAD="$LD_PRELOAD ./libsuperblt_loader.so" %command%

The loaders in each folder are different, as Arch and Fedora are usually a tad more up to date with libraries.