Use the emptys in the Collection Conveyor Industrial Rubber > Controlpoints

to adjust the conveyor belt to your needs.

In Collection Collection Conveyor Industrial Rubber > Look activate the Belt and the Style you need

If you need to place objects onto the belt activate Collection Conveyor Industrial Rubber > Conveyor Objects. There is only one object in there - essentially it is a triangle with a few modifiers - these modifiers are important.

Focus on the Displace modifiers - when changing the strength the placed objects will separate and place themselfs randomly - when changing strength to 0 - all objects are equally placed

The Array modifier on top can be used to space the objects appart - peek into it! 

Open Up the VertexWeightProximity.1 modifier - when changing the size/lenght of the conveyor belt the Values for Highest get mixed up - adjust them to cut off the objects on the beginning and the ending of the conveyor belt.