I'm looking for a JOOMLA's extension that would allow a user (candidate ) to upload files like Curriculum Vitae to their account. Thus another user (the employer) could access the files of the candidate user.
K2 has attachments option. You can setup it to allow candidates upload their Curriculum Vitae as attachments in the frontend. This guide explains how to configure the frontend submit form: https://www.joomreem.com/joomla-resources/k2-frontend-submit-items
Also, you will create a view access level which can access the items submitted by candidates, and assign this access level to the group of employers.
Then you need to set the access level of the K2 category (Curriculum Vitae) to the employers user group.