aldav53 ,
Connect the White Control Circuit Lead off the Photocell, to the other side of the 208 Volt 1Ø Circuit.
The Photocell's internal Relay Coil is designed to be driven from 208 Volts up to 277 Volts, so the Control Circuit must be within those parameters.
As it is now, the Control Circuit is only being driven at 120 Volts, so that internal Relay is most likely trying to pull in (may even be an audible "chirping" sound emitted).
I do agree with the use of Lighting Contactors for this type of Lighting option - mostly because the Photocell leaves a "Live" Ungrounded Conductor at each of the Fixtures when they are off during daylight hours, and someone may get "Shockenzeeassennoffer" (Shocked) if servicing a Lamp - due to the Screwshell being "Hot" still.
Multipole Contactors with all Ungrounded Conductors run through them, would reduce the potential for "Shokkenzeeassenoffer" by opening all the Ungrounded Conductors, plus eliminate the large load through the Photocell.
Not that this is a "Must Do" thing - you likely bid the job using a simple Photocell for the sole controller, and this is code compliant.
Anyhow, simply connect that White Lead to the "Other Side" of the 208 Volt Lighting Circuit, and the thing should work.
The Photocell's relay lead is "White" by "Default", so don't let that confuse you.
The White wire you used for the Photocell may be used to pull in a "Non-Identified Color" (i.e. Black, Red, Blue), which may be terminated to the "Other Side" of the 208 Volt Circuit at a convenient point - or if both Ungrounded Conductors run through the same box where the Photocell is at, simply terminate the White Photocell lead to the "Other Side" of the Circuit at that box.
Good luck! Let me know if smoke comes out