The reason this may occur is due to the fact that your applicant may be logging into the Form page rather than the Grantee Account page.

The difference is as follows:

Form page -

Grantee Account page -

The SID_#### is your foundation's Site ID and the FID is your form ID.
Bear in mind, navigating to and logging into the Form page will always create a new form. Navigating to and logging into the Grantee Account page, however, will allow your applicant to view their In-Progress and Submitted Applications and Requirements. If your applicant claims that when they log in, all they see is a new, blank form, forward them your foundation's Grantee Account page as a first step to see if this allows them to view their saved application forms.