This feature is available to users with Author level or higher permissions. Take a look at this article to learn more about the different access levels for a MailChimp account.
In order to track clicks in plain text emails, we have to replace your URL with one that points to our server first. You can't "hide" the URL tracking link, like you can with HTML emails. Instead, we have to redirect your recipients to a page we can monitor before we send them onto your site. It all happens in the blink of eye. Most people don't even notice it's happened.
So you might want to take a look at the following before activating click tracking in plain-text emails:
If this is what you create in your campaign:
Then, this is what you will see in your email program when it's delivered. If you want to track clicks in your plain text message, always make sure to give some instructions before or after your link. This lets people know where they're going when they click.
You must type out the full URL and include http://. We're unable to track links that are written out like www.mailchimp.com. Also, click tracking cannot be disabled in free accounts.