I too have been having the same problem.  I'm the admin of our account.  New employee received invite to their personal e-mail, tried on two occasions to set-up account but received the following error messages:

'Looks like you don't have a Workforce employee account.  The email you entered belongs to an admin account.  Only employees can access their Workforce accounts' and 'Oops something went wrong'.

Intuit should never have migrated from ViewMyPaycheck.  If it's not broke, don't fix it.