how do i add a mod map into my server

Download your map from the repo or here if you are running from a hosting website use the file manager that they should have insert your map then go to your startup options and put the name of the folder inside "levels" of the one your downloading / if you are using your own pc/connection its the same thing but instead go to AppData (you can do this by launching beam and clicking manage user folder and click on show in explorer.)
AppData > Roaming > BeamMP Launcher put mods into Rescources + Map go to ServerConfig and Change Map with the name of the map you downloaded INSIDE of LEVELS

https://forum.beammp.com/t/tutorial-how-to-use-a-custom-map-with-beammp-server/286