If you are told that the link has expired, it may be that you are using a link from an old mail.
If you ask for en a-mail to change your password, by clicking on the "Forgot password" button several times, you will receive several emails from First Agenda with a link to change your password. But it is only the latest received e-mail, that has the opportunity to generate the SMS code you need to complete changing your password. So for example if you click 3 times on the "Forgot Password" button and then receive 3 e-mails, it will only be the third e-mail / latest received e-mail, which will be able to generate a SMS code and allow you to change your password. If you use the link from the 1st or 2nd recieved e-mail, you will be told, that the link has expired.
The link can also expire if there has been a number of days before using it after recieving the e-mail. If so, then click on the "Forget password" button again to receive a new e-mail with a new link.