@Octavos_Folio Hi, they do spawn naturally. If you're having problems with it, it's likely you are exploring chunks that generated before you added the mod. Those won't have animals. As for configuration, please read the FAQ on the CurseForge page.
I've been porting an old mod of mine, [SBM] Fluid Gun, to 1.16.5! Planning on adding an upgrades system and possibly a "radius" upgrade to allow more than one block of fluid to be modified? Let me know what you think!
Here's a picture of the Ender Fluid Gun in action: