@Potato try the 8 Player Lobby mod that's already on the workshop. If I remember correctly, you need 4 people to join, then you start the game and have the rest join via a direct connection through an IP. You can check the server IP through the console. If nothing works, use sourcemod plug-ins to make it work.

a script that allows 5 people to play, can you create something like that for any game mode?

my man! thank you kindly good sir