When you launch Sencha Designer it should prompt you with a major update. Clicking the link, you should be able to download the Sencha Architect installer. Users who purchased Sencha Architect (or Sencha Designer Jan 1+) will be receiving emails with activation codes later today. Users who have not yet purchased Architect will receive a 30 day trial.
If you have purchased Architect and do not get an activation code in the next few days, contact firstname.lastname@example.org and we will take care of everything for you.