Can anyone help me understand Minecraft mods?

[dr.girlfriend]

DS is desperate to get a creatures mod for his Minecraft so that he can have scorpions, etc.  I tried to follow all the instructions, and it said the mod loaded, but when I play the game the creatures aren't there.  Does anyone think they can help me troubleshoot?  He's playing the Mac Edition.  I downloaded Forge, downloaded the mod (Custom Mob Spawner Mod 1.8) jar file and put it in the mods folder I created in Minecraft's Application Support.  I changed the profile to Forge when I started the game, and it says 4 mods loaded, and when I view the mods the custom mob spawner is one of them.  Any more ideas?

ETA:  Never mind, figured it out!  Apparently the directions are crap, you need Forge and the Custom Mob Spawner just as a basis, and then you also have to download the Mo Creatures mod.  Works now!