@Exile there's a line in the info.txt that reads "[REQUIRES_ID_AFTER_ME:vanilla_creatures_graphics]" this is to ensure people load this mod before vanilla graphics, as it wont function if loaded after—however, with how Dwarf Fortress' mod tokens work, this means the mod load order required "vanilla_creatures_graphics" in the load order, even though the mod itself doesn't actually depend on vanilla graphics. And DF wont allow you to create a new world if there are any missing/out of order mods based on their tokens.

If you have vanilla_creatures_graphics in your load order, make sure this mod is positioned above it. If you have another mod that removes/replaces vanilla_creatures_graphics (like nauts equipment graphics, or fantastic fantasy fortress, ect), remove the "[REQUIRES_ID_AFTER_ME:vanilla_creatures_graphics]" from this mod's info.txt, and load it before whatever mod you have that replaces vanilla graphics.

when I try to add these to a world it won't let me create the world, am I missing something?

Cows!

Amazing work once again! Good idea to add the known issues info, thanks for the quick reply about that on the other mod.