rebate offer

Hi! My mother, father and I all switched to T-Mobile. My mother and father got the $100 virtual card and my mom has been trying to get me to do this too but I can’t figure it out. My account is separate from theirs and I hope I can still do this and be eligible even though I’ve had the phone now for 2 months. Any info will be helpful. I’ve tried to do it on my own several times but can’t seem to find the correct starting point. Thanks so very much 💖