OK so

first: download the link of the desc.

second: put the stuff in the maps and scripts folders.

third: load the workshop map.

fourth: your gonna ask "OmG It DOsEnT woRk wHat dA HEcK!11!1!1"

fivth (i cant spell correctly): type this in the console commands. tf_mvm_popfile mvm_badwater_final

now this SHOULD show the wave on whats coming up. (note: i didnt test it lol)

edit: i forgot to say that you should type sv_cheats 1 before typing the command