Well, Forest Pack includes animation features, but it doesn't animate the geometry by itself. It gets the animation samples from the source object (currently, any of bundled presets aren't animated), i.e. animated meshes or procedural plants as GrowFX.
Unfortunately, in case of Octane renderer the Randomise and control animated geometry
feature isn't supported (current implementation returns only a pointer to the Custom Object in the scene and a transformation matrix, so all items are pure instances of the original geometry, and animation samples are ignored). You can see the list of supported features in our on-line reference guide