By default, new accounts have link tracking turned off so you will need to go your Tracking Settings to enable it.
If you would like to track how many contacts are opening emails and clicking links in your emails, you can enable open and link tracking by navigating to your Account Settings > Click the Tracking tab > Toggle Open Tracking and Link Tracking on.
Warning: Though this may be a feature you're interested in using, we do not recommend turning this feature on. This can cause a decrease in open and deliverability rates. Instead, we highly recommend setting up branded domains if you plan on enabling this feature.
Note: Activating this feature will not apply to emails that were sent previously but will be tracked for emails moving forward.