When a Daily Login Rewards event is active you'll earn rewards just by logging into the game during different days. After claiming a reward you'll see a count down timer for when your next reward will be available to claim.
You won't need to maintain a daily login streak and just need to log after the count down timer has refreshed to claim the next reward.
You'll have 21 days to complete a Daily Login Rewards track after claiming the first reward. In the future we plan to introduce new Daily Login Rewards tracks.
You'll only be able to make progress on one Daily Rewards track at a time so if you are still progressing through a Daily Login Rewards track when a new track becomes available you'll still be able to see the new Daily Rewards track but it will be locked for you until your active Daily Rewards track is completed or if 21 days have expired since you first claimed a reward from the track.