Where can people sign up for a new Zendesk Support trial?
You can sign up for a Zendesk Support trial here: https://www.zendesk.com/register/#getstarted
All Zendesk Support trials start out on the Professional plan. If you'd like to trial a different plan feel free to reach out to firstname.lastname@example.org to have your trial plan adjusted accordingly.
Please also note, the email you use to sign up should be for your own email contact, not necessarily the support addresses that your customers will be emailing--that's something you can set up after the trial is configured.