Are you trying to into the game, or just assemble a creature using the existing tools?
If you downloaded this file from a third-party source, ensure it is from a reputable community to avoid malware. Official custom content is best shared and downloaded via the Steam Workshop. Animal.Revolt.Battle.Simulator.rar
If you are looking to "put together" features beyond standard in-game tools (requiring external files from your .rar or other downloads): Are you trying to into the game, or
: To add entirely new models (like replacing human heads), you must rig a model in Blender, export it as an FBX, and use Unity to build an asset bundle for the game's StreamingAssets folder. If you are looking to "put together" features
: Modify stats like HP multipliers and detection distance to balance or overpower your creation. Advanced Modding Features