You can find the official article that explains the promotion here.
Final Beta start time
The Honkai: Star Rail final beta releases on Friday, 10th February at 2 am (GMT). Here's how it translates to other timezones:
UK - 10th February, 2 am (GMT),
East Coast US - Thursday 9th February, 9 pm (EST),
West Coast US - Thursday 9th February, 6 pm (PST),
Australia - 10th February, 1 pm (AEDT),
Japan - 10th February, 11 am (JST).
We don't know how long the beta will last, and none of the progress you make during it will transfer to the full release - this means there will be a wipe at the end of the final beta.
If you were one of the unlucky ones who didn't get picked during the most recent beta access lottery, now you will have a chance to get access to it again! How can you do it? Via Twitch Drops!
Twitch Drops is a feature on Twitch, whereby viewers can obtain game-specific rewards by watching streams. To participate in the Twitch Drops campaign, you have to connect your Twitch account with your HoYoverse Account.
Trailblazers who have yet to connect the Twitch account, please do so during the Twitch Drops campaign period and claim your rewards. After the campaign period, rewards will not be awarded.
You can connect your Hoyo and Twitch accounts by going here.
Once you do that, you have to wait for the Final Beta to start, watch any streamer who is playing Honkai: Star Rail for 1 hour and then claim the reward (March 7th frame) via Twitch.
Here's what the frame looks like:
The first 20,000 Trailblazers who successfully connect their accounts AND claim the Twitch Drops rewards will additionally obtain Honkai: Star Rail's beta testing qualification.
If you're not sure how this whole thing will work you can watch Tim's video who goes over the process.