There are a few main things to check if an autologin link is not working.
 
Is the email that is being used associated with an Admin account?
  • Using an Admin account to test is discouraged because it doesn't pull in personalizations in your emails and can cause other problems.  To test email always use an email that has a constituent account without Admin privileges.
 
Are you sending the email through Message Testing or Send this message to the Reviewer List?
  • You will want to use the Send this message to the Reviewer List option to get the best representation of how the email will look and function.  Make sure the emails in the Reviewer's list are non Admin accounts.  The autologin link in particular will not work if you send your email through Message Testing.