yes , in this mod you are not scoring at all , there's a button at the beginning of the map where you can start your time and one at the end of it where you stop it and that's it , the top15/nub15 is created in function of the time you make on the respective map.

So there's nothing I can do to make it count the time every player have on the server?

Time played on the server is not an accurate statistic for rank. I could sit on a server for days and be highly ranked. If you want time to count as rank, you could contact the mod developer to have the server report the time taken to complete the map as the players score.