Go to Settings > Status update settings and make sure that the first (enable "we received your application" message) and the third (enable editing) checkboxes are checked. Save the settings, and from now on all applicants submitting their applications will get a link in the confirmation email allowing them to edit the application. The link takes them to the same application form. It is recommended and in EU also mandatory due to GDPR, to keep this selected.
The applicant can edit their application as long as the application and the position remain active. After that, a message instructing applicant to contact the company will be shown.