If you need to host a meeting over 40 minutes and/or have up to 300 participants, you can request a Zoom license.
You can request a Zoom account by using the user account form.
You can access your licensed Zoom account by going to https://zoom.us and logging in.
The Zoom FAQ can be found here.
You don't need an account to participate in a Zoom meeting; please take a look here for more information.