This is for those attempting this through the weekly option.
You go to the NFL app. Select the "XBOX NFL PICK-OFF SWEEPSTAKES" ... You will notice to the left of the summary square is a set of grey square boxes. The first says Sweepstakes and prizes, and the remaining boxes are the things you can pick. The first is Team Tacklers followed by Super Catches etc.....
After you make your 5th selection and confirm....the challenge should pop.