UNOfficial Announcement. Rumor is you can get the Ash Prime Warframe if you log in within 7 days.

Grunty

Over 400,000 people logged in to watch the Warframe Twitch stream TennoLive2018.  The rule was if you had your Warframe account linked to your Twitch account and you watched 30 minutes of the stream then you would get the Ash Prime frame for free.

That 400,000 watchers  apparently broke their method of tracking who watched for how long.  Even the Warframe servers crashed for a little while.   

The in-game chat is unofficially saying that if you log into Warframe within the next 7 days you will get the Ash Prime Warframe for free.  That you didn't have to watch the twitch stream.  

As I said this is a rumor.  I haven't tried to corroborate it's truth or not.  People are in-game saying they have received Ash Prime but they did not watch the stream.

Panther2103

See I thought maybe the triggers broke for some people, because I logged in at the very end for 30 minutes, logged into Warframe and had my prime frame. But two people I know who watched the entire thing didn't get it. 

I'm hoping they fix this, as a lot of people Watched solely for that frame (I originally was but I got sucked into the cool announcements).

Grunty

Correction:

Anyone who has linked their Warframe account and Twitch account and logged into the game within the last 7 days will get Ash Prime.  You won't get it if you haven't linked your accounts.  If you didn't log in within the last 7 days then you won't get the frame.