Roller rejuvinator has 2 important uses.

1. Cleans of paper dust, which can cause rubber rollers to slip on paper causing creasing .
2. Rejuvinates rollers keeping rubber soft and grippy.  This both improves performance and life of the roller.

If you are folding glossy, coated for heavily printed papers, rejuvinator is more important. 

Easy to use.
Use conditioner AFTER the machine has had heavy use, generously ripe all accessible rubber rollers and leave to evaporate in.