You have to subtract the two vectors, so the node it use is Vector - Vector.
https://docs.unrealengine.com/latest…r_2/index.html
Then you take the length of the difference vector above and add it to the curent Distance (with a Set). In pseudo-code:
Distance := Distance + Length(GetActorLocation() - LastPosition)
Then you check if Distance > StepDistance and if true you make a step sound. After making the step sound you do
Distance := Distance - StepDistance
so you are ready for the next step.