If you already created an .abc mesh animation (using Ziva VFX or any other software), then you can always just play back that .abc inside the game engine. You don't need a Ziva product for that; you can use the engine's native abilities to play back an .abc.
If you are concerned about the .abc being huge, you can use ZivaRT to train a lean ZivaRT rig based on your .abc. Note that this will require setting up the character's skinning. You then don't need the .abc inside the engine, you can just use the ZivaRT rig which will decrease your memory footprint. This should enable you to play back your mesh animation inside the engine, modulo some loss of quality due to compression.
If you'd like to generate new motions inside the game engine, then you can also use ZivaRT to do that; however, this will require multiple .abc files spanning the typical range of motion of your character. You use those .abc files to train a ZivaRT rig.
ZivaRT is very fast, and available for Unreal Engine, Unity, and there's also a C/C++ implementation for custom engine integration. Note, however, that ZivaRT is not available to the general public like Ziva VFX. It is available to select customers based on a special commercial arrangement.