Zandronum

I am currently having problems as I wanna play Clusteruck but I dont know how the load order works. Can somebody explain it to me?

WADs are loaded one after the other when there's more of them, and the load order means the order in which these wads are loaded. An addon to a mod usually has to be loaded after the mod itself for everything to work. Find a server hosting Clusterfuck and you can see the server's wads and their ordering - try to replicate the load order of the server you find. The fact that the server is even up means they got the loading order right.