From Samsung's website - "Claims must be made via the Members app pre-installed on the device (individuals) or at https://www.samsung.com/uk/watch-active-offer (company) between 26/12/2020 – 11/02/2021."
So you should be okay to make your claim for your watch once your handset arrives. If not, contact Samsung's support.
Hope this solves your worries,
Has anyone got it working yet? I've tried for the last 3 hours and can't get it to appear. Tried deleting and reinstalling the app too. Updated device to newest firmware. Only got it today. Can someone please share the link so I can just fill out the form instead?