This behaviour can be due to several reasons:
1. Can Logon checkbox
As a versaSRS Administrator select the versaSRS Spinner icon > Administrators tab > Manage System Users > Select User > Edit.
Ensure that the username is correct and that the 'Can Logon' checkbox is ticcked.
2. Apostrophe in username and email
Ensure that the User does not have an apostrophe in their username and/or email, e.g. tom.o'neal@abc.com
NOTE: This issue has been fixed in versaSRS v7.2.0
3. Windows Authentication Configuration
If using Windows Authentication ensure that the username the User is logging on to their PC with is configured as their username in versaSRS.
4. ADFS Authentication
If using ADFS Authentication ensure that the alias email is set correctly as per this article.