You are no longer able to get the code via Twitch Prime, but if you DID get the code via Twitch Prime, you can enter it until July 25.

If you contact support about this they'll send you a code. Just make sure you submit it under "Code Redemption Problems" and mention Twitch Prime.

https://mtgarena-support.wizards.com/hc/en-us

@libXq#25580:

I am not a native speaker, but did I missed something? I think my understanding of the English language seems broken over all. In-game It says clearly "Get your Boros Legion deck today with Twitch Prime. Offer ends July 25."

We made a communication error. You can still get the deck you just have to contact our support team.