Missing operand expression builder trying to pull start date

Hello,

I am using the Employee Onboarding Module. In my workflow automator, I am trying to pull that start date and set 48 hours before it as the date the ticket is due. 

I was told by Freshservice that I need to use expression builder as so:

I have tried with _iso and without. I asked how that was an expression, and was told they’d submit a ticket for me and that should work.

I tried date(“{{ticket.onboarding_request.actor_1.cf_date_of_joining_iso}}”) and that didn’t work either.