Do I need a capacitor with the low voltage LYN400 control unit? The LYN400 instructions show I do but the Controll Unit instructions do not show it?

If you have the LYN400 24V (6 Wires) which is the low voltage version, then you do not need a capacitor for your motor(s), and a capacitor should not be used.

If you have the LYN400 230V (4 Wires) then a capacitor is needed and would have been supplied in the box with the motor(s).