Usually there is a link in one of the banners at the top of the Samsung Members app when you launch it on the phone that was bought to claim.
That or navigate back to the ee support pages that show the offer as there is often a link there to make the claim and look in their small print.
Can you link back to this particular offer please ?
Be sure to check eligibility dates.
I can see that ee are doing a cashback offer and YouTube offer on that particular phone.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I have no affiliation with Samsung.