Once you use the Samsung Shop app to register your device, you will need to await for the approval email. Once approved, you will need to wait an additional 24-48 hours to redeem. This email should come through some time this weekend. If you receive nothing by the end of the day on Monday 8/27, please let us know.
I can't get the samsung shop app because I live in the UK but when I opened fortnite launcher it still said if I played three matches then waited 24-48 hours I would still receive the skin in a gift box in game