On the dedicated server - as many lines like pb add You have in podbot.cfg as many bots will be added (unless it exceeds the cvar pb_maxbots). So if You have pb_minbots 0 and pb_maxbots 13 - to put 6 bots there You should have 6 lines pb add in podbot.cfg. But once You or someone else enters the game, one bot is kicked, so You can see there only 5 bots. The bot dll automatically controls the constant amount of bots + humans on the server. It depands on the number of lines pb add You were using (in podbot.cfg or in game) or of pb fillserver command. More info about that read
here.