He said "individual mob". It means only creeper will not spawn. Any mobs such as zombie or skeleton will still spawn, i presume.
A plugin or command block will help solving that problem
i already tried /kill @e[type=Creeper] with command block, it works but it lags up the server.i found a mod called "Bad mobs" but it's for previous versions. can i make it work on 1.16.2 ?