You can enable Two-factor Authentication by accessing “Two-factor Authentication (2FA)” under the "Settings" menu after you Sign In.
It is a simple best practice that adds an extra layer of protection on top of your user name and password. When a user signs in to Dropmysite, they will be prompted for their user email address and password (the first factor – what they know), as well as for an authentication code from the device (the second factor – what they have.) Taken together, the two factors provide increased security for your resources.More information
It must be installed on your mobile device. Please download it now.