If necessary, unlock the preference pane by clicking on the padlock in the lower left corner of the window, then enter your password. Once the padlock icon is in the open position, select the "Privacy" tab

Once in the Privacy tab, Scroll through the box on the left and select "Full Disk Access"

Check the box next to "Code42" in the "Full Disk Access" settings pane to allow Crashplan to backup your personal files.

The following message appears: "Code42" will not have full disk access until it is quit. Click Quit Now.