Synchronizing the walking or other animations and playing the appropriate sounds triggered by the animation causes the synchronization of the footfall sounds.
Footfall sounds are usually played via animation event of character’s animation. If the animation is played based on the character’s movement speed, just synchronizing the character movement by Strix Movement Synchronizer causes the synchronization of the animation automatically, and it results in the synchronization of the footfall sounds.
If your animations are not simply based on the movement speed, you will need to synchronize the animations using Strix Animation Sync or starting and stopping animations by RPC, but anyway it synchronizes the footfall sounds, too.