Obviously, and even recommended! As far as possible, it is important to discuss with the freelancer about the project , his / her skills and verify the professionalism and motivation of the freelancer.
So you can meet them, make a Skype, or have a telephone appointment with the freelance with whom you think to work.
However, for more security, make your conversations mails on the platform, so you will keep a history of all your messages, which can be useful in case of litigation.
Moreover, when you receive a notification by e-mail, you can reply directly to the notification message and this laste sent to the freelance will be recorded in your Khdemti mail.
It's even simpler than connecting to the platform and your exchanges remain secure and archived.