If you signed up before Aug 9, 2021, please click Previous plans to view your applicable plans.
Under the Customers tab, when you hover over an unverified contact, you will find an option to 'Send activation email'. Clicking on it will trigger an activation email to the respective contact.
Note:
It is not possible to re-send the activation link for a verified contact this way. However, you would be able to change the password share it with them or the contact could directly trigger a password reset.