Sharing some experience from a stressful day.
My parents arrived for an IR-5 immigration visa interview in Warsaw. All papers were in order, everything prepared as told, checked 100 times..
And at the entrance they are told that they can't enter the embassy if there is no profile for passport delivery details!
They had to go back to get their phones and create the profiles from the phones, on the website https://portal.ustraveldocs.com/applicanthome .
There you enter your name, passport number, mailing address for passport delivery.
It created an unnecessary delay and lots of stress. Additionally, for one of them the address in the profile was incorrect - we had to scramble to fix it after the interview via customer support.
The existence of this step is not communicated anywhere - not in NVC / CEAC website, not on State Dept website, not on the embassy website, and not in the interview invitation email.
Keep in mind. Maybe it's just for Warsaw embassy, maybe for more.
Also, they told us that unlike earlier years when you always got the passport with a visa next day (unless you got into administrative processing), it will be 3-5 business days here.